NỘI DUNG MÔN HỌC Foxpro

,NI DUNG MN HC Bao gm 2 phn Phn 1. H Qun tr CSDL FoxPro t s khi nim c bn c vi Fox ch ca s lnh Phn 2. Lp trnh FoxPro u bi ton c vi Fox ch lp trnh Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy PHN 1. H QUN TR CSDL FOX Ch-ng I. MT S KHI NIM C BN ...................... 5 I. C S D LIU V H QUN TR C S D LIU ............................ 5 I.1. Tin hc qun l ...................................................................................... 5 I.2. C s d liu .......................................................................................... 6 I.3. H qun tr CSDL Visual FoxPro 9.0 ..................................................... 6 II. CC KHI NIM C BN TRONG FOXPRO ...................................... 9 II.1. Cc kiu d liu c bn ....................................................................... 9 II.2. Hng v bin ..................................................................................... 11 II.3. Hm .................................................................................................. 12 II.4. Biu thc .......................................................................................... 12 II.5. Php gn ........................................................................................... 13 II.6. Lnh ................................................................................................. 13 III. FILE D LIU ....................................................................................... 14 III.1. H s ................................................................................................ 14 III.2. Bn d liu 2 chiu ........................................................................... 14 III.3. File d liu........................................................................................ 15 - 2

Ch-ng II. THAO TC VI FILE D LIU ................. 16 I. TO FILE C S D LIU ..................................................................... 16 I.1. To file c s d liu ........................................................................... 16 I.2. M v ng file c s d liu ............................................................... 18 II. LM VIC VI CU TRC FILE C S D LIU ........................... 19 II.1. Xem v in cu trc ............................................................................ 19 II.2. Sa cu trc ...................................................................................... 20 II.3. Trng c lp v khng c lp ...................................................... 21 Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh III. CP NHT D LIU CHO FILE C S D LIU ............................. 21 III.1. nh v con tr bn ghi ..................................................................... 21 III.2. Thm bn ghi .................................................................................... 24 III.3. Phm vi v iu kin trong cu lnh thao tc bn ghi ........................ 26 III.4. Xem v in d liu ............................................................................. 27 III.5. Sa d liu trn bn ghi .................................................................... 31 III.6. Xo bn ghi trong file c s d liu .................................................. 34 III.7. Thay th ni dung ca trng d liu ................................................ 36 III.8. Lnh Browse ..................................................................................... 37 IV. SP XP V TM KIM D LIU....................................................... 40 IV.1. Sp xp vt l ................................................................................... 40 IV.2. Sp xp logic .................................................................................... 42 IV.3. Tm kim tun t .............................................................................. 46 IV.4. Tm kim trc tip ............................................................................ 47 V. TNH TON V THNG K D LIU ............................................... 47 V.1. t lc cc bn ghi ........................................................................... 47 V.2. t lc cc trng ............................................................................. 48 - 3

V.3. m s bn ghi (Count) .................................................................... 49 V.4. Cng theo ct cc biu thc s (Sum) ............................................... 49 V.5. Tnh trung bnh cng (Average) ........................................................ 50 V.6. Tnh tng b phn (Total) ................................................................. 50 V.7. Thng k tng hp (Calculate) .......................................................... 52 Ch-ng III. LM VIC VI NHIU FILE CSDL ......... 53 I. VNG LM VIC - B DANH CA VNG LM VIC ........................ 53 I.1. Vng lm vic ...................................................................................... 53 I.2. B danh ................................................................................................ 55 II. TO MT FILE CSDL T MT FILE CSDL C .......................... 56 Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh II.1. To cu trc ...................................................................................... 56 II.2. To cu trc v a ni dung sang .................................................... 56 II.3. Kt ni 2 file CSDL .......................................................................... 57 II.4. Lnh UPDATE ................................................................................. 58 III. LIN KT CC FILE CSDL .................................................................. 60 III.1. t vn ......................................................................................... 60 III.2. Lin kt 1 chnh - 1 ph (1 - 1).......................................................... 60 III.3. Lin kt 1 chnh - n ph (1 - n).......................................................... 62 III.4. Lin kt mc xch ............................................................................. 63 Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy Ch-ng I. MT S KHI NIM C BN I. C S D LIU V H QUN TR C S D LIU I.1. Tin hc qun l - 5 - 4

Ni n tin hc ta khng th khng nhc n my tnh. My tnh l mt cng c tin hc nhng n khng th thay th cho con ngi. My tnh do con ngi ch to ra, v my tnh c th thc hin mt cng vic no , con ngi cn phi vit chng trnh cho n lm vic. Lc u my tnh sinh ra nhm mc ch gip con ngi gim nh cng vic tnh ton v tng tc tnh ton. Nhng hin nay vi s pht trin nhanh chng ca tin hc, n ang tng bc thm nhp vo rt nhiu lnh vc trong i sng x hi v my tnh khng ch n gin dng tnh ton m my tnh ch yu gip con ngi s dng thng tin, v ng dng ca tin hc nh my tnh ch yu 2 lnh vc c k thut: lin quan n tnh ton phc tp vi khi lng ln (chim 20%). V d. phn mm thng k, phn mm k ton, phn mm v qun s... n l x hi: tnh ton n gin nhng cc mi quan h li phc tp phi x l mt khi lng ln d liu (chim 80%). V d. phn mm qun l khch sn, qun l bn hng, qun l khu vui chi... Tin hc qun l l mt ngnh ng dng tin hc trong cng tc qun l. Bi ton qun l gm cc c trng sau l mt khi lng d liu kh ln, lun bin i v c cp nht thng xuyn. c cp nht thng c t chc theo nhng khun mu nht nh gi l cu trc d liu. Cc mu ny c thit k sao cho ph hp vi cc yu cu x l khc nhau. V d o Mu Ho n thu chi qun l ti chnh, o Mu phiu xut, nhp kho qun l hng trong kho, o Mu h s cn b qun l cn b... phn loi cc bi ton qun l theo tng lnh vc chung. V d o Qun l kho thnh phm ca cng ty bnh ko Hi H

Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh o Qun l kho thnh phm ca x nghip in c Thng Nht n l kho. o Qun l mua bn hng ti mt ca hng vn phng phm o Qun l mua bn hng ti mt quy sch n l bn hng. Bi v v mt nghip v chng c nhng im tng ng vi nhau. t qu x l thng tin trong bi ton qun l thng a ra theo dng mu biu. Khi qun l v x l thng tin phi m bo 4 mc tiu y t qun o mt - 6

V phi bo m cc thao tc c bn i vi h s i tng qun l o To lp (Create) o Cp nht: update, delete, change. o Sp xp (sort) o Tm kim (find, seek) o Lc (filter) o Tnh ton: cng (count), tng (sum), trung bnh (average)... o Bo co (report) I.2. C s d liu C s d liu l mt tp hp d liu ca mt t chc c lu tr trong my tnh, c nhiu ngi s dng v vic thc hin n c chi phi bng mt m hnh d liu.

Ch : Mt c s d liu khc mt ngn hng d liu v c s d liu l d liu c t chc c cu trc gip cho vic thc hin mt cch thun li, thao tc c bn thun tin. I.3. H qun tr CSDL Visual FoxPro 9.0 u tin ta ni n mi quan h gia Databate, Management, System. Hot ng qun l thng phi x l mt khi lng ln thng tin v thng yu cu phi nhanh, chnh xc nn i hi phi c tin hc ho. Tin hc Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy ho cng tc qun l l mt i ng hng, trong cng c chnh ca vic tin hc ho l cc phn mm hng vo cng tc qun l. Tc l nhng phn mm ny phi tr gip cho con ngi 4 mc tiu v 7 thao tc c bn nu. Nhng phn mm nh vy c gi l cc H qun tr C s d liu. C rt nhiu H qun tr c s d liu nh FoxPro, Access, Oracle, DB2... FoxPro = Fox Professional. Trong mn hc s gii thiu phin bn Visual FoxPro 9. Ci t FoxPro for Windows Chy file setup.exe v chn la ch ci t t y t tng thnh phn t ti thiu chy. Vo/ra FoxPro khi ng FoxPro di chuyn chut Start/Programs/Microsoft Visual FoxPro 9.0. Sau khi khi ng, mn hnh lm vic ca FoxPro xut hin. Khi thot khi FoxPro ta c 2 cch i ca s lnh dng lnh Quit. - 7

o n phm F10 o Chn bng chn File o Chn mc Exit Cng c th thc hin bng cch chn phm nng n Alt + F, n phm X. Hai ch lm vic trong Visual Fox Cng ging cc phin bn khc, Visual Fox cng lm vic hai ch : ch hi thoi (ca s lnh) v ch chng trnh (lp trnh). hi thoi: ngi dng g mt lnh vo ca s lnh, cui lnh n Enter, my thc hin lnh, kt qu lnh a ra mn hnh chnh, FoxPro li sn sng ch lnh tip. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh chng trnh, ta cn to mt file vn bn gm cc lnh ca FoxPro, sau chy file ny. S dng h thng bn chn n phm F10. t sng n bng chn cn thit v n phm Enter. Khi mt bng chn dc xut hin pha di bng chn va chn t sng n mc cn chn v n phm Enter. u phn la chn no cn c ngha l cn la chn mc trong, ta tip tc s dng cc phm mi tn di chuyn n mc cn chn v n Enter. Son tho vn bn trong FoxPro M mt file vn bn mi hoc gi mt file c bng lnh MODIFY COMMAND ng dn \ tn file - 8

V d: MODIFY COMMAND C:\My document\hocsinh.txt Sau khi son tho xong, ghi vn bn vo a v ng ca s son tho, hy n Ctrl + W Cc phm dch chuyn con tr n phm mi tn ch con tr ln/xung mt trang mn hnh v u/cui dng. v u/cui vn bn. Thay i ch chn/ dng phm Insert nh du khi vn bn nhy nt tri chut v ko, khi vn bn c mu xanh. Dnh du ton b vn bn Ctrl+A. Hu nh du khi: nhy nt tri chut. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy Cc thao tc chnh khi son tho xo khi v ghi vo vng m sao chp khi vo vng m chp khi t vng m vo ch con tr. i. tm kim v thay th dy k t in : Ctrl + G khng thay v tm kim tip thay v tm kim tip t c. t lp cc c tnh mn hnh son tho. II. CC KHI NIM C BN TRONG FOXPRO II.1. Cc kiu d liu c bn Trong FOXPRO c 8 kiu d liu c bn: u k t Character (C): Cha cc k t thuc bng m ASCII c rng - 9

ti a 254 k t, phn bit ch hoa v thng. u s Numeric (N): Cha d liu kiu s nguyn v s thc. (Bao gm C c s t 0 - 9, du dng (+), du m (-) v du chm thp phn). C rng 20 k t s. u Float (F): Cha d liu kiu s thc vi du phy ng. V d: 1 = 123.45) u Date (D): Cha d liu dng ngy thng vi rng c nh l 8. Dng ngm nh l MM/DD/YY. C th chuyn sang DD/MM/YY bng lnh Set Date French. u Logic (L): Nhn hai gi tr True (T) hoc False (F) c rng c nh l 1. u Memo (M): Cha cc khi vn bn ln c rng khng qu 64.000 k t. u Picture (P) v General (G): Cha hnh nh, m thanh v bng tnh. Cc php ton cho cc kiu d liu hc (dng cho kiu N, F) theo th t u tin Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy Lu tha: ** hoc ^ (khng giao hon) VD: 3 5 = 3**5 (3^5); 10 100 = 100**(1/10). Nhn, chia: * (giao hon), / (khng giao hon). - 10 12.34500000E+01 (=12.34500000 x 10

Cng, tr: + (giao hon), - (khng giao hon) Cc ton hng c kiu N s cho ra kt qu kiu N. i k t (cng mc u tin) Php cng: ghp 2 chui thnh 1 chui (ghp nguyn vn). Php tr: ghp 2 chui thnh mt chui nhng chuyn tt c nhng du cch cui chui 1 v cui chui kt qu. VD. a = thanh pho ; b = Ha noi ? a + b = thanh pho Ha noi ? len(a+b ? a b = thanh phoHa noi ? len(ai kiu ngy (cng mc u tin) Php cng: +

VD. Date() D D N ng kiu L cho ra kt qu kiu L. snh. Hai ton hng phi c cng kiu, kt qu php ton c kiu L, l T nu so snh ng, l F nu so snh sai. Lut so snh p dng cho cc kiu nh sau + Kiu C: so snh theo m ASCII Generated by Foxit PDF Creator Foxit Software ng cch gia 2 ngy>

http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy + Kiu N, F: so snh theo gi tr i s + Kiu D: theo trc thi gian + Kiu L: gi tr .F. nh hn gi tr .T. Cc php ton = v == (so snh chnh xc) l nh nhau i vi kiu: N, D, L v khc nhau i vi kiu C. i vi = s .T. nu ni dung v phi l phn u ni dung v tri T i vi ==: ch ng nu 2 chui ging nhau hon ton. dng cho kiu C). Kt qu c II.2. Hng v bin Hng l i lng c gi tr khng thay i. ng kiu s: -12, 123.45, 0,12, 1.2E-6... ng k t: t trong cp du hoc hoc [ ]. VD Ha noi... ng logic c hai gi tr l .T. v .F., hoc .Y. v .N. ng kiu ngy: t trong cp du { }. VD {12/04/01}. Ngy rng k hiu l { } hoc { / / }. Bin l i lng c gi tr c th thay i. FoxPro chia bin thnh 3 loi n nh l cc bin trung gian c to ra khi chy chng trnh hay thc hin cc lnh trong khung ca s lnh. C th gii phng cc bin nh khi khng cn dng na. n trng l tn mt trng ca c s d liu. Bin trng tn ti trong khi c s d liu cha n c m. n h thng do FoxPro t to ra trong b nh ngay sau khi khi ng. Bin h thng c tn bt u bng du gch di. ng T nu bn tri l tp con ca bn phi. - 11

Hng v bin c lu tr ni dung trong b nh trong thng qua tn hng v tn bin c t theo quy tc: tn di ti a 10 k t, c th dng ch, ch s, du gch chn, nhng khng c bt u bng s v khng c du cch. Tn bin khng phn bit ch hoa v ch thng. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh Hng v bin trong FoxPro khng cn phi nh ngha kiu d liu trc m kiu d liu ca n s c xc nh khi n c gn ni dung. Kiu hng v bin tng ng vi cc kiu d liu c bn (khng xt kiu G). = hoc store to hoc tt c cc lnh trong FoxPro c phn ...to . II.3. Hm L cng c to gi tr cho cc i lng hay s dng trong gi tr thao tc. Hm c tn, i s hoc khng c i s. Tn hm t theo quy tc t tn file nu hm do ngi dng t vit, khng t tn trng vi tn hm th vin. Cc hm do FoxPro cung cp sn, khi s dng ch cn xc nh 4 ch ci u, cn cc hm do ngi dng t vit th phi c vit tn y . Mt hm (khng c i s hoc c i s th gi tr i s phi xc nh) ch tr li mt gi tr duy nht v c kiu xc nh l 1 trong 4 kiu C, N, D, L. Cnh tn hm bao gi cng phi c cp du (). Nu c i s th cc i s c vit trong cp du ngoc ny, nu nhiu i s th ngn cch nhau bi du phy. VD. Cc hm th vin li ngy gi h thng. li mt chui k t th hin gi hin ti. II.4. Biu thc - 12

Biu thc l t hp cc hng, bin, hm v cc php ton. VD. Biu thc n gin l tn 1 bin, 1 hng. Trong mt biu thc, cc php ton c thc hin theo th t u tin, php ton s hc v ghp xu thc hin trc, sau n cc php so snh, cui cng l php logic. Cc php ton cng mc u tin c thc hin t tri sang phi. Mun thay i th t u tin ta dng cp ngoc trn. Tuy nhin trong tp cc biu thc th FoxPro ch chp nhn cc biu thc hp l VD. DATE()/3 l biu thc khng hp l. (32) l biu thc hp l. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh II.5. Php gn C php = Lnh ny nhm khi to mt bin mi v gn gi tr ban u cho n. II.6. Lnh Lnh l mt thao tc yu cu FoxPro thc hin mt cng vic no do ngi s dng yu cu. C php chung vit lnh [Phm vi] [DS trng] [For ] [To / ] Trong Lnh: L cc lnh bt k, phi vit ng c php, ch cn vit 4 k t u. Phm vi: Ch vng tc ng ca lnh. DS trng: Ch nhng trng c lit k trong dach sch mi c tc ng, gia cc trng cch nhau bi du phy. For : Ch nhng bn ghi tho mn biu thc iu kin mi c thc hin. To /: a kt qu ra file hoc my in. - 13

Ch : Nhng thnh phn vit trong < > l bt buc phi vit ra. Cn nhng thnh phn vit trong [ ] l ty chn. V d khi chn FOR th nht nh phi vit Cch dng lnh. nh bao gm t kho, cc tham s, cc phn tu chn khng phn bit ch hoa, ch thng. Khi vit lnh phi vit ng c php lnh. C php lnh l quy tc lnh. Khi vit sai c php s nhn c thng tin bo li Syntax error. ch chng trnh o Nu mi lnh c vit trn mt dng (ti a 3000 k t) th cui dng lnh khng vit bt c du no. o Nu mi lnh c vit trn nhiu dng th cui mi dng (tr dng cui cng) phi dng du ;. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy ch hi thoi o Mi lnh c vit trn mt dng (c th vit trn nhiu dng, cui dng c du ;), khi nh s c thc hin. - 14

o Trong mt phin lm vic, cc lnh c lu tr ton b trong ca s lnh nn ta c th s dng li cc lnh ging hoc tng t cc lnh sp dng bng cch a con tr n lnh . Nu ging th thc hin, gn ging th sa cho ng ri thc hin. n dng cc lnh ca MS - DOS trong ca s lnh hay trong file chng trnh ta phi vit t kho RUN hoc ! ri n lnh bnh thng ca DOS.

V d. Run Dir *.* ! Dir /p kho lnh nu c nhiu hn 4 ch ci th ch cn vit 4 ch ci u. V d Disp stru t lnh bt buc phi c 1 ng t lnh, nu thiu chng trnh s thng bo li unrecognize command verb. III. FILE D LIU File d liu l i tng s dng chnh trong h qun tr CSDL vn bn. III.1. H s Xt mt tp cc i tng qun l, i tng ny c t tng ng vi mt vn bn lit k cc thng tin v i tng y. Mi vn bn nh vy c gi l mt h s. VD. L lch c nhn, h s v cc c quan, ho n bn hng, phiu im... III.2. Bn d liu 2 chiu Xt mt tp hp h s c cng bn cht v cu trc (h s ca cc i tng cng loi khi x l th cng), ngi ta thng lp cc bng bao gm cc ct hng. VD. Bng trch ngang l lch, bng im ca sinh vin, danh sch lp. Thng thng cc bng ny b hn ch bi kch thc giy. y ta a ra khi nim bng d liu 2 chiu t tng t duy trn nhng ch m rng thm l khng hn ch bi kch thc giy, bng d liu 2 chiu gm cc ct cc dng tng ng vi chiu dc v ngang. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy hiu dc gm cc ct, mi ct ng vi 1 thng tin c trng m h s no cng c. Nh vy nu mi h s c nhiu thng tin c trng th bng phi c nhiu ct. u ngang gm cc dng, mi dng ng vi mt h s v ngc li - 15

mi h s ch ng vi mt dng. III.3. File d liu T khi nim bng d liu 2 chiu trn, lu tr c bng ny rong b nh ca my tnh in t, cc h QTCSDL cho php to lp v lu tr file c t chc mt cch c bit nhm th hin trn mn hnh hoc giy in hnh nh nh bn trn giy. ng thi gip ngi lm cng tc qun l thc hin c thun li cc thao tc c bn. File nh vy c gi l file d liu. Trong file d liu Mi ct trong bng gi l mt trng (field) v c t tng ng vi mt bin, bin ny c gi l bin trng. Mi dng c gi l mt bn ghi (record). Nh vy mi h s tng ng vi mt bn ghi trong file. File d liu c c trng bi 2 phm tr cu trc v ni dung. u trc l cc thng tin v cc trng gm: tn, kiu, rng, i vi kiu N c thm phn l thp phn. + Tn trng (name): t theo quy tc t tn bin. + Kiu trng (type): c 5 kiu C, N, D, L, M (M thc cht l kiu C nhng khng xc nh trc c rng) + rng (width) i vi mi file d liu cu trc ca n c to mt ln sau c th sa cha. Mun xo cu trc phi xo file d liu. i dung: l tp hp cc bn ghi. Lc u khi cu trc va c to th file cha c ni dung gi l file rng. i vi cc bn ghi ca file d liu c th thm, sa, xo gi chung l cp nht (update). C th xo ht tt c cc bng ghi v file tr nn rng. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy - 16

Ch-ng II. THAO TC VI FILE D LIU I. TO FILE C S D LIU I.1. To file c s d liu Khi ta mun lu tr mt tp cc h s cng loi, mi h s c c trng bi mt s cc thng tin c trng nh nhau. V d, h s ca cc gio vin trong khoa, phiu im ca mi sinh vin trong mt hc k... Khi ta thit k cu trc file d liu tng ng gm i thng tin c trng c biu din l mt trng. V d, h s cc gio vin trong khoa c cc trng nh: h tn, ngy sinh, hc hm, hc v, mn dy... vo dng ca thng tin c trng m ta khai bo cc thuc tnh cho cc trng: tn trng, kiu d liu, rng v phn l (nu c). V d, ngaysinh c kiu D, hoten c kiu C... Vic thit k c ghi vo mt bng c cc ct STT, tn trng, kiu trng, rng, phn l thp phn, ghi ch (ghi tng minh tn trng, min gi tr...). Mi dng ca bng ny ng vi mt trng ca file c s d liu. Nu h s c n thng tin d liu c n trng trn n dng.

V d, xt tp cc h s l tp cc phiu im ca sinh vin bao gm cc thng tin c trng sau: M sinh vin, h tn, ngy sinh, gii tnh, im cc mn hc, im trung bnh, xp loi, hc bng, ghi ch. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy STT Tn trng Kiu rng Phn l Gii thch 1. maSV C 7 M s sinh vin 2. hoten C 27 H v tn sinh vin 3. nsinh D 8 Ngy sinh 4. gtinh L 1 Gii tnh (Nam - T; Nu - F) - 17

5. thoc N 2 im tin hc [0,10] - 6 vht 6. tanh N 2 im ting anh[0,10] - 5 vht 7. triet N 2 Trit hc [0,10] - 5 vht 8. xlech N 2 X lch [0,10] - 2 vht - n hc 9. xkep N 2 X kp [0,10] - 2 vht - nam hc 10. dtb N 5 2 im trung bnh 11. xloai C 10 Xp loi hc lc 12. hbong N 6 Hc bng 13. gchu M 9 Qu trnh hc tp v rn luyn C 3 cch to file c s d liu Cch 1. To qua khung i thoi. G lnh c c php vo ca s lnh Create ]: ch hin tr nhng trng lit k trong c th sa cha. V d. a ra h tn, ngy sinh, im trung bnh, xp loi ca cc sinh vin trong file CSDL DIEM.DBF sa cha

m vi>] : chn phm vi thao tc trn mt s bn ghi nht nh, nu khng c th coi nh l ALL. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy LE ] : c ngha tng t nh trong lnh DISPLAY | LIST, nhng thay bi vic hin th, y dng son tho ni dung cc bn ghi. ng>] : ch cho php sa i d liu trong mt trng ch ra bi , con d liu trong cc trng khc ch c th hin th m khng cho sa i. V d. a ra h tn, ngy sinh, im tin hc, im trung bnh, xp loi ca cc sinh vin trong file CSDL DIEM.DBF nhng ch cho php sa i trn trng im tin hc. use - 33

t tiu khc cho ca s EDIT (mc nh l tn file CSDL m ta m ra sa). V d. Chng ta mun tiu ca s trn l Thay doi diem tin hoc thay bi diem chng ta thc hin lnh sau

hin th thng tin bng lnh EDIT m khng cho sa i. o bn ghi mi bng lnh EDIT. Lc ny nu ta n + s khng c tc dng. u xo bn ghi bng lnh EDIT. Lc

ny nu ta n + s khng c tc dng. 2 ca s EDIT mt lc theo chiu ngang trang mn hnh, l ca s bn tri (Left) v ca s bn phi (Right). Trong ch ra rng ct ca ca s bn tri. V d.

Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy 2 ca s EDIT mc nh ca s khi lnh EDIT bt u thc hin l ca s bn phi. Trong trng hp ta mun thay i khi bt u lnh EDIT ta thm vo iu khon ny. Thao tc chuyn i gia 2 ca s l + . V d. - 34

hin th thng tin trn ca s EDIT di dng chiu ngang mn hnh (mi bn ghi l mt dng). III.6. Xo bn ghi trong file c s d liu II.III.6.1 . nh du xo (xo logic) nh du xo cc bn ghi trong file CSDL ta s dng lnh DELETE c c php nh sau DELETE [] [FOR ] [WHILE ] Nu khng c iu khon no i km th lnh ch nh du xo bn ghi hin ti. Mt bn ghi b nh du xo th hm delete() s tr li gi tr l .T. V d. Ch xem nhng bn ghi no cha b nh du xo list for not delete() set delete on / off (on: b qua bn ghi b nh du xo) Cc iu khon c ngha tng t nh trong cc lnh khc.

Ch . Cc bn ghi b xo bi lnh DELETE y ch b xo v mt logic, thc ra v mt vt l nhng bn ghi ny vn tn ti trn a, nhng b nh du xo, chnh v vy nu s dng nhng lnh xem ni dung file CSDL nh EDIT,... th chng ta vn thy nhng bn ghi ny, nhng u tn cc trng b nh du. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy Nu cc bn ghi b nh du xo bng lnh DELETE m cha b xo v mt vt l, ta c th khi phc li nhng bn ghi ny bng cch thc hin lnh RECALL RECALL [] [FOR ] [WHILE ] Phm vi ngm nh l bn ghi hin ti. V d. Xo bn ghi ca nhng sinh vin c im trung bnh di 5 trong file CSDL diem.dbf. - 35

Khi phc bn ghi ca nhng sinh vin c im trung bnh ln hn 4 trong file CSDL diem.dbf.

II.III.6.2 . Xo vt l xo b hon ton cc bn ghi ra khi a v mt vt l ta s dng lnh PACK c c php nh sau PACK [MEMO] [DBF] Xo hn nhng bn ghi b nh du xo, sau lnh ny cc bn ghi khng khi phc li c. u khng c iu khon no i km th lnh PACK c tc dng vi tt c cc bn ghi b nh du xo. tc dng ln trng MEMO ca cc bn ghi b nh

du xo. tc dng trn cc trng khc ngoi trng MEMO. Vic thc hin lnh PACK nh sau c gi nguyn trn a nhng c i tn thnh *.bak (*.tbk) lu phng h. o ra cc file *.dbf (*.fpt) c cu trc nh file ban u. ng bn ghi khng b nh du xo sang file mi, sau nhn thng bo s lng bn ghi c copy sang. Ngoi ra FoxPro cn cung cp lnh ZAP xo ton b ni dung ca file CSDL k c cc bn ghi c b nh du xo hay khng b nh du xo. Ch . Cn thn khi s dng lnh ZAP, v lnh ny s xo tt c cc bn ghi trong file CSDL hin ti v khng c cch no khi phc li. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy - 36

pack III.7. Thay th ni dung ca trng d liu gn ni dung cho mt bin nh ta c th dng php gn = hay dng lnh store to . Nhng cc cch ny ch c s dng cho bin nh. i vi bin trng gn gi tr cho n ngoi vic nhp ra ta cn c th dng lnh REPLACE c c php nh sau. REPLACE WITH [ADDITIVE] [, WITH [ADDITIVE]]... [] [FOR ] [WHILE ]

Phm vi ngm nh ca lnh l bn ghi hin ti, kiu biu thc phi ph hp vi kiu trng. ng 1> WITH : tn trng cn thay th m gi tr ca s c gn cho n. i thm d liu vo mt trng c kiu MEMO. Cc iu khon khc c ngha tng t nh trong cc lnh khc. V d. Tnh im trung bnh, xp loi hc lc v phn hc bng cho file CSDL diem.dbf vi gi tr mi trng c lp l y .

replace all dtb with (tin*6 + anh*4 + triet*3 + iif(gtinh,xkep,xlech)*2)/(6+4+3+2) Trng xloai c tnh theo quy tc sau t

i t sc replace all xloai with xuat sac for dtb>=9 replace all xloai with gioi for dtb>=8 and dtb=7 and dtb=5 and dtb : R - (read only) d liu ch hin ln mn hnh khng cho sa. V d - 38

ng> : V = btL1 [:F] [:E = btC1] - (veify) kim tra gi tr nhp vo khi sa i hay thm mi cho trng ny c tho mn hay khng. m tra gi tr trng ngay c khi n khng thay i. l thay v Ivalid Data (ngm nh) V d. browse fields masv,hoten, thoc:V=between(thoc,0,10):F:E=Du lieu sai browse fields masv,hoten,nsinh:V=nsinh : N: cho php th hin rng ca trng trn mn hnh theo N ct. V d. browse fields masv :7,hoten :27,dtb :5 ng> : P = - chui khun dng quy nh dng d liu nhp vo. ! : cc d liu kiu k t s chuyn thnh ch hoa 9 : nhn gi tr dng s v du (-), dng (+) cho d liu kiu N, gi tr ch s cho kiu C A : ch cho nhp ch ci # : ch cho nhp gi tr l s, k t trng hoc +, . : v tr du chm thp phn , : v tr du phy ngn, triu, t L : ch cho nhp gi tr logic (T, F, Y, N) N : ch cho php nh vo d liu dng k t v dng s X : nhn bt k k t no - 39

Y : ch cho php nhn Y y N n V d. m sinh vin ch nhn 2 k t u l ch, 5 k t sau l s, h tn l ch hoa browse fields mv:p=AA99999,hoten:p=@! ng> :B = , : quy nh cn di v cn trn cho gi tr ca trng. Hai biu thc ny phi cng kiu (s, k t, ngy). V d. browse fields hoten:R,nsinh:R, thoc:p=##:b=0,10 ng> :H = (heading): thay i tiu mc nh ca tn trng thnh tiu . V d. browse fields hoten:h=padc(Ho va ten,27) pad(, n, []) : n vo cho rng n k t (nu c), mc nh l du cch. n 2 bn n bn tri n bn phi ng> :W= (when): chi cho truy nhp vo trng khi ng. V d. Nhp im x lch v x kp Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy browse fields hoten:R,nsinh:R, xkep:W=gtinh,xlech:W=not gtinh Ch . :F v :E ch dng vi :B v :V. :E s a ra thng bo li theo ngi dng, mc nh - 40

thng bo li ny bng ting anh. V d. browse fields hoten:R,nsinh:R, thoc:p=##:b=0,10:e=diem tu 0 den 10 L1>]: ch hin th cc bn ghi tho mn . V d. a ra danh sch nhng sinh vin c im trung bnh di 4. browse fields hoten,nsinh,dtb for dtb] : Ch c cc trng c ch nh trong mi c ghi vo file d liu mi. V d. To mt file mi c sp xp theo th t gim dn ca dtb, trong ch c nhng ngi t 5.0 tr ln v cc trng gm masv, hoten, nsinh, dtb. sort to diemdat on dtb/D all for dtb>5 masv,hoten,nsinh,dtb - 41

Ch . nh SORT ch dng kho sp xp l mt trng, khng dng mt kho l biu thc tng qut, tc l kho c cha bin nh v hm. t qu sau khi lnh thc hin trng thi ng, mun xem li phi m ra. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy Nhn xt c im: tn b nh v mi tiu chun sp xp sinh ra mt file, nu cp nht thm d liu th phi sp xp li. m: nhn c 1 file c sp xp m cc thao tc trn file khng cn quan tm. IV.2. Sp xp logic Sp xp d liu ch c tin hnh trong b nh trong cn file d liu khng thay i. Vic sp xp do mt file khc iu khin gi l file ch s (Index). File ch s ny c cu trc c bit m ta khng nhn thy c nhng ta c th hnh dung n nh l mt file d liu ch c 2 trng 1. Lu tr gi tr ca vic sp xp 2. Lu tr s hiu cc bn ghi file d liu c cng gi tr vi gi tr kho sp xp. V d. Gi s c tp hssv.dbf gm cc bn ghi Record# hodem 1 2 3 4 5 ten nsinh 20/07/77 - 42

Nguyen Hoai Anh Pham Kim

Phuong 25/04/78

Nguyen Thanh Huyen 05/12/77 Nguyen Bich Ngoc Phan Quang Binh 05/12/78 27/10/79

Nu sp xp theo th t abc ca trng tn th tp ch s (v d l Csten.idx) s gm hai ct Gi tr kha Anh Binh Huyen Ngoc Phuong 1 5 3 4 2 Recno

Khi ta cn tm kim mt ngi c tn l Binh, my s tm ct th nht ca tp ch s n gi tr kho l Binh, dng sang ngang ta c tm c l bn ghi th 5 trong file d liu. u im ca file index l c kch thc nh dng tra cu hoc tm kim rt nhanh i vi file CSDL gc. II.IV.2.1 . To file Index C php Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy INDEX ON TO [FOR ] u thc kho sp xp> : l tn trng hay mt biu thc hp l trong FoxPro. Vic sp xp lun theo th t tng dn c n sp xp - 43

theo th t gim dn ta phi lp l nghch bin theo gi tr . o file ch s .IDX. To xong, file ch s c m, con tr bn ghi nm bn ghi c ch s kho thp nht. V d. Sp xp logic theo dtb theo chiu gim dn use diem

index on -dtb to iddiem display all masv,hoten,nsinh,dtb cc bn ghi tho mn biu thc logic mi c sp xp V d. Sp xp logic theo dtb theo chiu gim dn i vi cc sinh vin c im trung bnh t 5 tr ln use diem index on -dtb to iddiem for dtb > 5 display all masv,hoten,nsinh,dtb u mun sp xp theo nhiu ch tiu vi cc mc u tin khc nhau, ta i kho ny ra cng gi tr xu (bng hm dtoc()) ri ghp chng li theo th t u tin t tri sang phi thnh biu thc kho. V d. Sp xp logic theo hoten, cng hoten theo nsinh set date french use diem index on hoten + dtoc(nsinh) to idnsinh display all masv,hoten,nsinh,dtb V d. Sp xp logic theo gtinh, cng gtinh theo hoten, cng hoten theo nsinh set date french use diem index on iif(gtinh,A,B) + hoten + dtoc(nsinh) to idgtinh display all masv,hoten,nsinh,dtb s s iu khin sp xp d liu ngay khi n c to ra. Nu ta to ra nhiu file ch s cho cng 1 file d liu th file ch s c to ra cui cng s iu khin vic sp xp d liu trn file CSDL . Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy - 44

II.IV.2.2 . Thao tc vi file Index a. M file ch s C 2 cch m file ch s: m file CSDL ri sau m file ch s, m cc file ch s ng thi vi file CSDL. s file CSDL c m, m cc file ch s ta dng lnh SET INDEX TO [ORDER | ] Sau lnh ny tt c cc file ch s trong u c m, nu khng c iu khon [ORDER | ] th mc nh file ch s u tin trong s l file ch s ch. o : tn cc file ch s ca file CSDL cn m. o [ORDER | ] : file ch s c th t l (hoc ) trong va m s l file ch s ch. o Nu dng iu khon ORDER 0 th cc file ch s c m khng c file no l file ch s ch. V d. M file ch s idhoten, idnsinh, iddiem, idgtinh ca file CSDL diem set date french use diem set index to idhoten,idnsinh,iddiem,idgtinh V d. M file ch s idhoten, idnsinh, iddiem, idgtinh ca file CSDL diem trong file idnsinh s l file ch s ch. set date french use diem set index to idhoten,idnsinh,iddiem,idgtinh order 2 hoc set index to idhoten,idnsinh,iddiem,idgtinh order idnsinh hoc set index to idnsinh,idhoten,iddiem,idgtinh file ch s ng thi vi vic m file CSDL

USE INDEX TO [ORDER | ] Cc iu khon trong lnh ny ging nh vi cch 1. V d. M file ch s idhoten, idnsinh, iddiem, idgtinh ca file CSDL diem Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh set date french use diem index to idhoten,idnsinh,iddiem,idgtinh b. Chuyn i file ch s ch Khi c nhiu file ch s ang hot ng ta c th thay i file ch s ch bng lnh SET ORDER TO | Sau lnh ny file ch s c th t l theo th t va m (hoc c trong cc file ch s va m) s l file ch s ch. c. ng file ch s ng tt c cc file ch s ang m i vi CSDL hin ang s dng ta dng lnh SET INDEX TO d. Ch s s b ng nu file CSDL ca n b ng. nh SET ORDER TO 0 s a file d liu v th t vt l ban u trong khi file ch s vn c m. Nn dng cch ny cp nht d liu. p nht file d liu th file ch s ch c cp nht khi n c m. p nht file d liu m qun cha m file ch s, ch s ho li cho file ch s ta c th thc hin theo 2 cch sau c hin li lnh sp xp. file ch s bng lnh bit, sau thc hin lnh - 45

REINDEX. Lnh ny cp nht tnh trng mi nht ca file CSDL u file ch s c m, ta xt cc trng hp sau u m ln lt tng file ch s th file ch s c m cui cng quyt nh vic sp xp cn cc file trc ng l

mt file ch s mi cng s bao hm vic ng cc file ch s m. u m ng thi danh sch file ch s th file ch s ng u trong danh sch quyt nh vic sp xp. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy p: Thc hin sp xp logic trng hoten theo nguyn tc: sp xp theo tn, nu trng tn sp theo hodem. Vi gi thit trng hoten trong file CSDL c chun ho (cc ch ci u t vit hoa cn cc ch ci khc vit thng, mi t cch nhau bi 1 du cch). dng tr th n xut hin xu c1 trong xu c2. y n k t ca xu s k t k t th i. y n k t bn tri ca xu s. i - 46

vitri+1) -1) index on substr(allt(hoten), rat( ,allt(hoten))+1) + left(allt(hoten), rat( ,allt(hoten))-1) to idten IV.3. Tm kim tun t

Tm kim tun t l cng vic khi ta tm kim d liu theo mt iu kin no th vic tm kim s tin hnh duyt bn ghi t trn xung, con tr bn ghi s dng li bn ghi u tin m iu kin ng, nu khng c bn ghi no nh vy trong file th con tr bn ghi nm im cui file. C php LOCATE FOR Lnh ny nh v con tr bn ghi vo bn ghi u tin (theo th t trn xung) thuc tho mn . Nu khng c th lnh LOCATE s tm kim trn tt c cc bn ghi. Nu tm thy, hm FOUNT() c gi tr .T., hm RECNO() cho s hiu bn ghi va tm thy. xem ni dung ca bn ghi va tm thy ta dng lnh DISPLAY. Nu khng tm thy hm FOUND() cho gi tr .F., hm EOF() cho gi tr .T. tm tip cc bn ghi m ng ta s dng lnh CONTINUE. V d. Tm trong file diem.dbf ngi c m sinh vin l TN00036 use diem locate for TN00036 Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh display Nhn xt. m: cho php tm thy tt c cc bn ghi m iu kin ng. c im: tc chm. i cch tm kim ny d liu trong file khng cn c sp xp. IV.4. Tm kim trc tip Vic tm kim s c tin hnh nhanh hn nu ta sp xp d liu. tm kim trc tip d liu cn c sp xp logic v iu kin tm ch c thit lp trn kho sp xp. C php - 47

SEEK Lnh ny s nh v con tr bn ghi vo bn ghi u tin c gi tr kho trng vi gi tr ca . c th nhn cc kiu C, D, N, L Nu tm thy hm FOUND() cho gi tr .T. Nu khng tm thy hm FOUND() cho gi tr .F. Nhn xt. m: tc nhanh. c im: ch thy bn ghi u tin m gi tr kho trng vi trong bn ghi. i cch tm kim ny d liu trong file cn phi c sp xp. V. TNH TON V THNG K D LIU V.1. t lc cc bn ghi C php SET FILTER TO Lnh ny to mt lc trn CSDL ang m. Sau lnh ny ch c cc bn ghi tho mn mi c tham gia vo qu trnh x l. Ch . nh lc ny mt tc dng khi gp mt trong cc lnh sau Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy o Lnh t mt lc khc thay th. o Lnh hu t lc: SET FILTER TO o Lnh ng file CSDL: USE hi thoi sau khi lnh lc c thc hin n tc dng ln file d liu ngay. Trong ch chng trnh b lc khng tc ng ln file d liu ngay nu nh sau khng c lnh lin quan - 48

n con tr bn ghi. nh lc khng lm thay i con tr bn ghi lin sau , do ta thng phi iu chnh li con tr bn ghi bng lnh GO TOP. c s lm lin tc ho cc bn ghi, hay s dng trong chng trnh in. V d. t lc cho file CSDL diem ch x l trn cc bn ghi l sinh vin nam. use diem set filter to gtinh = .T. display all

V d. t lc cho file CSDL diem ch x l trn cc bn ghi c dtb > 5 v thoc < 4. use diem set filter to (dtb > 5) and (thoc < 4) display all V.2. t lc cc trng Gi s c mt file CSDL ang m v ta lm vic vi tt c cc trng. Mun hn ch s trng lm vic ta dng lnh SET FIELDS TO Tt c cc lnh thc hin sau lnh ny ch lm vic vi cc trng c trong . Sau khi t lc, ta c th tt hoc bt ch t lc cc trng nh lnh SET FIELDS OFF hay SET FIELDS ON Khi ng file CSDL th lc cng mt. Ch . Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox

Gio vin: Nguy nh SET FIELDS TO s b sung thm trng mi vo danh sch trng ca lnh t lc trc. nh SET FIELDS TO ALL tr li trng thi s dng tt c cc trng. V d. use diem set fields to masv,hoten,nsinh,dtb display all V.3. m s bn ghi (Count) C php COUNT [] [FOR ] [WHILE ] [TO ] Lnh ny m s bn ghi thuc tho mn iu kin ca (hoc ). Phm vi ngm nh l ALL. Nu khng c phn to th gi tr tnh c s hin ra mn hnh. Nu c to gi tr tnh c s c gn cho . Nu cha c s sinh ra, nu c ri s in ln. Lnh COUNT s tr li s bn ghi c trong file (tng t lnh RECCOUNT) nhng trong trng hp ny ta nn dng hm RECCOUNT(). V d. Tnh % s hc sinh nam c trong lp. use diem count for gtinh to sonam ? sonam/reccount() * 100 V.4. Cng theo ct cc biu thc s (Sum) C php SUM [] [] [FOR ] [WHILE ] [TO ] Lnh ny tnh tng trn cc bn ghi thuc tho mn iu kin ca (hoc ). Phm vi ngm nh l ALL.

- 49

Nu khng c [] th ton b trng s trong file s c cng. Nu khng c phn to th kt qu hin ra mn hnh ngc li gi tr kt qu c gn cho bin. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy Gi i l s biu thc c cng j l s bin nh Nu i = j: gn tng ng i > j: gn n khi ht bin th dng. i < j: li c php. V d. Tnh im trung bnh cho mn hc thoc. use diem sum thoc to diem ? diem/reccount() V.5. Tnh trung bnh cng (Average) C php AVERAGE [] [] [FOR ] [WHILE ] [TO ] Lnh ny ly trung bnh cng trn cc bn ghi theo . Phm vi ngm nh l ALL. C php ca lnh ny hon ton ging lnh SUM. Kt qu ca vic tnh trung bnh l h qu ca 2 php tnh trn. V d. Tnh trung bnh lng chnh ca n v 1. use luong average lchinh for donvi = 01 to tb count for donvi = 01 to so1 - 50

sum lchinh for donvi = 01 to tong1 ? tong1/so1 V d. Tnh trung bnh cho mn thoc. use diem average thoc to dtb V.6. Tnh tng b phn (Total) C php TOTAL TO ON [] [FIELDS ] [FOR ] [WHILE ] Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh Lnh ny tnh tng cc trng kiu s ca cc bn ghi c l nh nhau. V d tnh tng lng chnh ca tng n v, tnh tng s sinh vin ca tng lp,... Kt qu tnh c s a ra mt file mi trn a. File mi t ng sinh ra c u trc ca file mi tng t file CSDL gc (i vi trng khng phi kiu s th ging ht, i vi trng s th tn v kiu ging, rng t ng m rng). i dung: nu file CSDL gc c n gi tr khc nhau th file ny c n bn ghi. Cn ni dung ca tng bn ghi s c lu nh sau o i vi trng khc s th lu ni dung bn ghi u tin n gp i vi d liu kho file gc. o i vi trng s th ghi tng n cng c theo b phn. t qu nhn c trng thi ng, mun dng th phi m. Nu c iu khon th ch c cc bn ghi nm trong phm vi mi - 51

c lnh TOTAL xt n. Nu c iu khon [FOR ] [WHILE ] th ch c cc bn ghi tho mn biu thc logic mi c lnh TOTAL xt n. Nu c iu khon [FIELDS ] th ch c cc trng kiu s c lit k trong danh sch trng mi c tnh tng v a ra tp kt qu cc trng s cn li ly gi tr ca bn ghi u tin trong . Ch u d liu khng c sp xp theo kho b phn th lnh vn thc hin bnh thng nhng khng nhn c kt qu mong mun v lnh TOTAL c thc hin bng gii thut ngt cc bc. o tng ca gii thut ngt cc bc: gi s cn gii quyt bi ton c 2 cng vic A v B th ngi ta xy dng mt bin C v ni dung ca bin l tp hp cc gi tr no y. Cng vic A s c thc hin lp i lp li chng no gi tr ca bin C cha thay i, khi gi tr ca bin C thay i th ngng cng vic A lm cng vic B. Cng vic trn c lp li cho n khi duyt ht gi tr ca bin C. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy o i vi bi ton tnh tng b phn th bin C l kho b phn, cng vic A l cng vic cng dn, cng vic B l ghi kt qu nhn c ca vic cng dn ln file mi. u trng tip nhn khng rng lu tr kt qu th trng ny s b trn s. V d. Tnh tng s sinh vin t im 5, 6, 7, 8, 9, 10 trong mn thoc. use diem sort to sapxep on thoc for thoc > 4 - 52

use sapxep total to baocao on thoc use baocao display all V.7. Thng k tng hp (Calculate) Lnh CALCULATE l khi qut ca cc lnh COUNT, SUM, AVERAGE. Lnh ny cho php tnh nhiu gi tr khc nhau trong mt ln duyt CSDL. C php ca lnh ny ging nh lnh SUM. SUM [] [] [FOR ] [WHILE ] [TO ] Trong [] l danh sch hm ly t hm mu sau CNT() : m s bn ghi SUM(): tnh tng theo AVG(): tnh trung bnh cng theo MAX(): tnh gi tr ln nht theo MIN(): tnh gi tr nh nht theo V d. Tnh tng s sinh vin b im di 5 trong tng mn hc v tnh im trung bnh cho tng mn hc. use diem calculate cnt(thoc),cnt(triet),cnt(tanh), cnt(xlech),cnt(xkep),avg(thoc),avg(triet), avg(tanh),avg(xlech),avg(xkep) to x1,x2,x3,x4,x5,x6,x7,x8,x9,x10 ? x1,x2,x3,x4,x5,x6,x7,x8,x9,x10 Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy Ch-ng III. LM VIC VI NHIU FILE CSDL - 53

I. VNG LM VIC - B DANH CA VNG LM VIC I.1. Vng lm vic Vng lm vic l mt khu vc ca b nh m trong khu vc y ti mt thi im ta ch c th m c 1 file d liu. FoxPro for Windows cho php ngi dng m ng thi ti a 225 file CSDL vi iu kin ta phi ch nh nhng vng lm vic khc nhau cho mi file CSDL c m. Nu khng, khi ta m file th hai bng lnh USE th file th nht b ng li v chng cng nm trn mt vng. V d. Khi ta mun thao thc vi 2 file d liu diem.dbf v sinhvien.dbf, ta khng th dng lnh USE diem USE sinhvien V khi ta m file sinhvien th file diem s b ng bi v chng cng nm trn mt vng lm vic. Khi mi khi ng FoxPro ngm nh l vng 1, cc vng lm vic c nh s t ny c gi l s hiu ca vng. Cc vng lm vic cn

c FoxPro t t tn theo quy tc t ch ci t i vi 10 vng lm vic u tin v t

i vi 215 vng cn li. t s t ng vi 225 vng

t tn no c gi l b danh. s dng mt file m mt vng no ta phi chuyn n vng lm vic bng lnh SELECT c c php SELECT | V d. Ta m file diem.dbf ti vng 1, file sinhvien.dbf ti vng 2. lm vic vi file sinhvien.dbf ta thc hin lnh SELECT 2 Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox

Gio vin: Nguy Khi m 1 file CSDL ti 1 vng xc nh c 2 cch n n vng lm vic , v m file bnh thng SELECT 2 USE sinhvien mt vng bt k, thc hin lnh USE IN | USE sinhvien IN 2 USE diem IN 1 Cch dng ny thng bo cho FoxPro m 2 file CSDL hai vng khc nhau v chng lun trng thi sn sng lm vic. ng file CSDL ti mt vng no n n vng lm vic v ng bnh thng SELECT 1 USE mt vng bt k thc hin lnh USE IN | USE IN 2 USE IN 1 Lnh CLOSE DATABASE s ng tt c cc file CSDL c m cc vng lm vic v chuyn v vng ngm nh (vng 1). Ta c th s dng lnh CLOSE ALL ng cc file CSDL c m. Ch u mt file c m mt vng xc nh m mun m li n mt vng khc th sau lnh m file phi c t kho AGAIN (nu khng c t kho ny FoxPro s thng bo li file c dng). m li mt file nhiu vng, nhng file m li ch c xem ch khng c truy nhp.

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nhiu file, nu ta khng nh cc vng c file c m, c th dn n m file ny v ng nhm file c m. Lnh SELECT 0 cho php chuyn v vng c s hiu thp nht m cha c mt file no c m. a s th hin trng thi ca cc vng.

Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy Kt lun Vic s dng cc vng lm vic khc nhau, lm tng tc thc hin cng vic, v khng phi m li file v rt thun tin khi cng vic i hi phi x l nhiu file c lin quan n nhau. Vic nh vng lm vi khng nht thit phi theo mt th t no. Khi m nhiu file CSDL trn cc vng khc nhau, cc lnh dch chuyn, nh v con tr bn ghi vng ny hon ton khng nh hng n con tr bn ghi vng khc tr khi chng lin kt vi nhau bi lnh SET RELATION. I.2. B danh Khi m 1 file CSDL trnh cho ngi dng phi nh file c m vng no. FoxPro cho php gn mt b danh (t theo quy tc t tn bin) theo quy nh u m file bng nhng lnh bit th tn file mc nh l b danh. u m file bng lnh USE ALIAS , c chn s lm b danh cho vng. Khi mt vng c b danh m mun chuyn n vng ta dng lnh SELECT Nhn xt i nhiu file d liu cc vng khc nhau ta cn nh lnh SELECT 0, SELECT v khi nim b danh ni chung - 55

m khng cn bit file c m vng no. n trng lm vic ca file no ch tn ti trong vng lm vic ca file . V vy, khi ta mun truy cp n bin trng ca mt file CSDL c m vng khc, ta c 2 cch o Cch 1: Chuyn n vng c file cha bin trng , thc hin cc thao tc nh bnh thng. o Ti mt vng bt k ta s dng . o V d. ta c th truy cp vo bin trng hoten ca file diem.dbf bng cch diem.hoten. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguyn Hoi Anh II. TO MT FILE CSDL T MT FILE CSDL C II.1. To cu trc Cc bc thc hin file CSDL c dng lnh COPY STRUCTURE c c php COPY STRUCTURE TO [fields ] Lnh COPY STRUCTURE cho php ngi dng to mt file CSDL mi c cu trc ging file CSDL c sn. File CSDL mi c to trng thi ng hon ton cha c d liu, nu mun s dng ta phi dng cc lnh bit m. Nu c iu khon [fields ] th ch cc trng c trong mi c copy. II.2. To cu trc v a ni dung sang Cc bc thc hin file CSDL c dng lnh COPY c c php COPY TO [fields ] - 56

[FOR ] [WHILE ] Lnh COPY cho php ngi dng to mt file CSDL mi c cu trc ging file CSDL c sn v cc bn ghi ca file ny cng s c copy sang file mi. File CSDL mi c to trng thi ng, nu mun s dng ta phi dng cc lnh bit m file ny. Nu c iu khon [fields ] th ch cc trng c trong mi c copy. Nu c iu khon [FOR ] [WHILE ] th ch cc bn ghi tho mn iu kin mi c copy sang file mi. V d. T file diem.dbf ly ra file CSDL gm trng masv, hoten, nsinh, dtb vi iu kin c nhng sinh vin t yu cu use diem Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy copy to dat fields masv,hoten,nsinh,dtb for dtb >=5 c nhng sinh vin c hc b mn no c im di 5) use diem copy to hocbong fields masv,hoten,nsinh,dtb for (dtb>=5) and (thoc>=5) and (tanh>=5) and (triet>=5) and iff(gtinh,xkep>=5,xlech>=5) c nhng sinh vin phi thi li mt mn no use diem copy to thi lai fields masv,hoten,nsinh,thoc,tanh,triet,xlech,xkep,dtb for (thoc m : nhng bn ghi di ra ca file 1 ng vi im cui ca file 2. o n < m : nhng bn ghi di ra ca file 2 khng t tng ng vi bn ghi no ca file 1. Ngi ta thng gi file 1 l chnh, file 2 l ph. tin hnh lin kt 2 file bng cch ny ta phi thc hin cc bc sau 2 file 2 vng khc nhau vng c file chnh c m ta thc hin lnh SET RELATION TO RECNO() INTO - 61

V d 1. Phng Qun l sinh vin lu tr sinh vin khoa CNTT trong file SVCNTT.DBF (masv, hoten, nsinh, quequan) - Phng gio v lu tr thng tin v im cui k ca cc sinh vin trong file DIEM.DBF (masv, thoc, triet, tanh, dtb). Gi s th t ca sinh vin 2 file l nh nhau. nhn c thng tin y v sinh vin ta phi tin hnh lin kt 2 file select 0 use diem select 0 use SVCNTT set relation to recno() into diem display all fields masv,hoten,nsinh,diem.dtb for dtb >= 5 Nhn xt. Vic tin hnh lin kt 2 file nhm mc ch lin kt con tr bn ghi hai vng khc nhau, tc l khi con tr bn ghi file chnh chuyn ng ko theo s chuyn ng ca con tr bn ghi file ph. V d 2. Ti mt ca hng kinh doanh vng bc, qun l gi vng trong 2 thng 7 v 8 ngi ta lu vo 2 file TH07.DBF v TH08.DBF (mi bn ghi l mt ngy). Hy a ra bng so snh gi vng ca tng ngy trong thng 7 v 8. select 0 use th07 Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy select 0 use th08 set relation to recno() into th07 display all fields th07.ngay,th08.ngay,th07.gia,th08.gia 2. Lin kt nh s so snh gi tr ca 2 trng trong 2 file - 62

Tc l xc nh mt nh x gia 2 trng c dng so snh c gi l trng lin kt, hai trng ny phi ging nhau v kiu v rng, cn tn khng nht thit phi ging nhau. thc hin lin kt 2 file vi nhau cn c vo ng ngha ca bi ton ta chn mt file lm file chnh, file con li lm file ph ri thc hin 2 file 2 vng khc nhau p xp logic file ph trn trng lin kt ca n vng c file chnh c m ta thc hin lnh SET RELATION TO INTO V d. Thc hin bi ton lin kt file HOSO.DBF v file MATINH.DBF select 0 use matinh index on ma to idma select 0 use hoso set relation to mtinh into matinh Browse nomodify fields masv,hoten,matinh.ten Vi v d 1 trn, ta gii quyt c trong trng hp tng qut, nu thc hin lin kt thng qua trng masv. select 0 use diem index on masv to idmasv select 0 use SVCNTT set relation to masv into diem Browse nomodify fields masv,hoten,nsinh,diem.dtb for dtb >= 5

III.3. Lin kt 1 chnh - n ph (1 - n) y l n lin kt chnh ph, ch c 1 file chnh v n file ph. Ta phi thc hin n lnh lin kt 1 file chnh vi 1 file ph. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy Ch t lnh SET RELATION th 2 tr i phi thm t kho ADDITIVE, nu khng thm t kho ny th cc lin kt trc s b hu b. V d. B sung vo file HOSO.DBF cc trng madt C(2), maut C(2) v 2 file MADTOC (ma C(2), ten C(13)) v MAUTIEN (ma C(2), loai C(20)). Tin hnh lin kt file HOSO vi 3 file m. HOSO mtinh madt maut matinh(ma) madtoc(ma) mautien(ma) select 0 use mautien index on ma to id1 select 0 use madtoc index on ma to id2 select 0 use matinh index on ma to id3 select 0 - 63

use hoso set relation to mtinh into matinh set relation to madt into madtoc additive set relation to maut into mautien additive Browse nomodify fields masv,hoten,matinh.ten,madtoc.ten,mautien.loai III.4. Lin kt mc xch Xt n file CSDL, lin kt mc xch l lin kt n - 1 lin kt chnh ph, trong 1 file l file chnh duy nht, 1 file l file ph duy nht, nhng file cn li va l chnh ca file ny va l ph ca file khc. Ch . T lnh SET RELATION th 2 tr i phi thm t kho ADDITIVE, nhng khng c lin kt mc xch thnh vng trn. V d. Bi ton ghp phch TSINH(sbd C(5), hoten C(27), nsinh D) PHACH(sbd C(5), ph C(5)) DMON(ph C(5), diem N(4.1)) select 0 use dmon Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.Bi ging H qun tr CSDL Fox Gio vin: Nguy index on ph to id1 select 0 use phach set relation to ph into dmon index on sbd to id2 select 0 use tsinh - 64

set relation to sbd into phach Browse nomodify fields hoten,sbd,nsinh,dmon.diem Trong thc t loi chng ta thng gp l t hp ca 3 loi lin kt trn. Generated by Foxit PDF Creator Foxit Software http://www.foxitsoftware.com For evaluation only.

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