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DBMAN7
PL/SQL introductionControl StructuresExercisesCursorsExceptionsProcedures, TriggersTrigger exercise
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DBMAN7
PL/SQL introductionControl StructuresExercisesCursorsExceptionsProcedures, TriggersTrigger exercise
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TRADITIONAL SQL PROCESSING• Common tasks:
– Special tasks that can not be done in SQL or that are not SQL-specific tasks
– Relatively simple processing of big amount of data– Checks before update/insert/delete
• Even when using localhost, it is better to do these on the server
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TRADITIONAL SQL PROCESSING• Common tasks
– More than one type of clients– Some function must be implemented It has to be
done separately for every language– Some common functions are not advised to be
implemented this way• Even when using localhost, it is better to do these on the
server
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PL/*• The server has two engines: the SQL engine and the PL/*
engine: Procedural Language Engine• It is usually a problem-oriented/procedural language,
that allows us to do different programming tasks on the server
• Therefore, the server does some of the calculations/methods (usually those methods require a lot of data – high-load applications are not advised!)
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PL/*
• Using PL/* programs, we can:– Execute simple, embedded script-code using
different structures– Create and use PROCEDURES for common
functions– Use special error handling: EXCEPTIONS– Create special procedures that are executed
automatically (e.g. to check something before insert/update/delete): TRIGGER
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PL/*http://www.stanford.edu/dept/itss/docs/oracle/10g/appdev.101/b10807/01_oview.htm
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PL/*• Oracle uses a language that has an SQL-like syntax:
PL/SQL• PostgreSQL: PL/PGSQL, PL/PERL (2), PL/PYTHON, PL/TCL,
PL/JAVA (2), PL/PHP, PL/R, PL/RUBY• Embedded language vs. PL language
• PL-SQL: Probably the oldest and the most widely used Procedural Language
• A PL/PGSQL in PostgreSQL is similar, little differences GOOGLE
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PL/SQL SEQUENCE• DROP SEQUENCE myseq;• CREATE SEQUENCE myseq START WITH 10000
INCREMENT BY 1;• CREATE TABLE logs (
log_id INT PRIMARY KEY,log_when TIMESTAMP,log_entry CLOB
);• INSERT INTO logs VALUES (myseq.nextval,
SYSTIMESTAMP, ‘DB RESET’);
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PL/SQL BLOCK
• A separated area in the SQL script-program, that is interpreted by the PL/SQL engine
• We’ll use the sql developer from inside the VM• Syntax:SET SERVEROUTPUT ON[DECLARE {variables}]BEGIN
{commands}[EXCEPTION
{exception handling}]END;/
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VARIABLES
• Client-side variables:SET VERIFY ON;ACCEPT sal1 PROMPT 'Lower Bound?';ACCEPT sal2 PROMPT 'Higher Bound?';SELECT * FROM emp WHERE sal>&sal1 AND sal<&sal2; („SUBSTITUTE VARIABLES”)
• Server-side variables: DECLARE {name} {type}; RW in the PL/SQL, Nonexistant outside („LOCAL VARIABLES”)VARIABLE {name} {type}; Usually RW in the PL/SQL, R outside („BIND VARIABLES”)
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set verify off;set serveroutput on;ACCEPT var_I PROMPT 'WRITE
SOMETHING! ';VARIABLE var_II number;
DECLARE var_III number;BEGIN :var_II := &var_I; var_III := :var_II; DBMS_OUTPUT.PUT_LINE('block 1'); DBMS_OUTPUT.PUT_LINE(:var_II); DBMS_OUTPUT.PUT_LINE(var_III); DBMS_OUTPUT.PUT_LINE('ends');END;/PRINT var_II;
DECLARE var_III number;BEGIN var_III := :var_II; DBMS_OUTPUT.PUT_LINE('block
2'); DBMS_OUTPUT.PUT_LINE(:var_II); DBMS_OUTPUT.PUT_LINE(var_III); DBMS_OUTPUT.PUT_LINE('ends');END;/BIND variables depend on the client
as well (e.g. prepared statements)
VARIABLES
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VARIABLE TYPES• Basic SQL types• Reference types
– {table}.{column}%TYPE;– {variable}%TYPE;– {table}%ROWTYPE; Record type ~ Pascal
• Record: varname.colname
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ROWID• Automatically generated unique ID for each row in a
database• "Secret column", like the rownum• select emp.*, rowid, rownum from emp;• Can be used to match the output rows in different
output records
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FUNCTIONS• Traditional functions
– UPPER(s), LOWER(s), MOD(x, n)– TO_CHAR(x[, s]), TO_DATE(d, s)
• Random number / text:– http://www.psoug.org/reference/dbms_random.html– dbms_random.value(),
dbms_random.value(2, 5)
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DBMAN7
PL/SQL introductionControl StructuresExercisesCursorsExceptionsProcedures, TriggersTrigger exercise
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SELECT Order of suffixes
1. INTO2. FROM3. WHERE4. GROUP BY5. HAVING6. UNION/MINUS7. INTERSECT8. ORDER BY
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SELECT INTO• SELECT {field(s)} INTO {variable(s)} {other suffixes}• The query must return with exactly one row!• The query must return with exactly as many fields as
many variables we list after the INTO• Or: whole record %ROWTYPE
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SELECT INTO
DECLARE var NUMBER;BEGIN SELECT empno INTO var FROM emp;END;/
• ORA-01422: exact fetch returns more than requested number of rows
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SELECT INTO
DECLAREvar NUMBER;var2 EMP%ROWTYPE;
BEGIN SELECT empno INTO var FROM emp WHERE ename='KING'; SELECT * INTO var2 FROM emp WHERE ename='KING';END;/
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IFIF {condition} THEN
{commands}[ELSIF {condition} THEN
{commands}][other ELSIF clauses][ELSE
{commands}]END IF;
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LOOPLOOP {commands}END LOOP;
To break the loop:• EXIT;• EXIT WHEN {condition};
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WHILEWHILE {condition}{LOOP}
set serveroutput on;DECLARE
var NUMBER;BEGIN var:=0; WHILE var<=5 LOOP DBMS_OUTPUT.PUT_LINE(var); var:=var+1; END LOOP;END;/
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FOR
FOR {variable} IN {lower} .. {higher}{LOOP}
set serveroutput on;DECLARE
var NUMBER;BEGIN FOR var IN 0 .. 5 LOOP DBMS_OUTPUT.PUT_LINE(var); END LOOP;END;/
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FOR . . .set serveroutput on;set verify on;accept A prompt 'Enter a number:'accept B prompt 'Another number:'DECLARE J NUMBER(5);BEGIN FOR j IN &A..&B LOOP DBMS_OUTPUT.PUT_LINE(j); END LOOP;END;/
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SET VERIFY ON(default in sql-developer)
SQL> @x.sqlEnter a number:4Another number:9
old 3: for j in &A..&Bnew 3: for j in 4.9
FOR j IN &A .. &B
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DBMAN7
PL/SQL introductionControl StructuresExercisesCursorsExceptionsProcedures, TriggersTrigger exercise
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EXERCISES• N!• NM
• GCD (Greatest Common Divisor)• LCM (Least Common Multiple)
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N!
ACCEPT num1 PROMPT 'First number (N)! ';
DECLARE res number;j number;
BEGIN res := 1; FOR j IN 1 .. &num1 LOOP res := res * j; END LOOP; DBMS_OUTPUT.PUT_LINE(res);END;/
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NM
ACCEPT num1 PROMPT 'First number (N)! ';ACCEPT num2 PROMPT 'Second number (M)! ';
DECLARE res number;j number;
BEGIN res := 1; FOR j IN 1 .. &num2 LOOP res := res * &num1; END LOOP; DBMS_OUTPUT.PUT_LINE(res);END;/
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GCD
ACCEPT num1 PROMPT 'First number (X)! ';ACCEPT num2 PROMPT 'Second number (Y)! ';
DECLAREX NUMBER;Y NUMBER;
BEGIN X:=&num1; Y:=&num2; WHILE X<>Y LOOP if (X<Y) THEN Y:=Y-X; END IF; if (X>Y) THEN X:=X-Y; END IF; END LOOP; DBMS_OUTPUT.PUT_LINE(X);END;/
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LCMACCEPT num1 PROMPT 'First number (X)! ';ACCEPT num2 PROMPT 'Second number (Y)! ';-- LCM = (X*Y) / GCD(X,Y)DECLARE
X NUMBER;Y NUMBER;C NUMBER;
BEGIN X:=&num1; Y:=&num2; C:=X*Y; WHILE X<>Y LOOP if (X<Y) THEN Y:=Y-X; END IF; if (X>Y) THEN X:=X-Y; END IF; END LOOP; DBMS_OUTPUT.PUT_LINE('GCD : '||X); DBMS_OUTPUT.PUT_LINE('LCM : '||C/X);END;/
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DBMAN7
PL/SQL introductionControl StructuresExercisesCursorsExceptionsProcedures, TriggersTrigger exercise
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FOR – IMPLICIT CURSOR
set serveroutput on;DECLARE
someone emp%ROWTYPE;BEGIN FOR someone IN (SELECT * FROM emp) LOOP DBMS_OUTPUT.PUT_LINE('Name = ' ||
someone.ename); DBMS_OUTPUT.PUT_LINE('Salary = ' || someone.sal); END LOOP;END;/
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DECLARING A CURSORDECLARE
var1 NUMBER(5);var2 EMP%ROWTYPE;CURSOR var2 IS
SELECT * FROM EMP;
The query is not executed, we only declare that the given variable will refer to the given query
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USING CURSORS [FOR]
ACCEPT low_sal PROMPT 'Lower bound! 'ACCEPT upp_sal PROMPT 'Upper bound! 'DECLARE CURSOR curs IS select * from emp; record EMP%ROWTYPE;BEGIN FOR record IN curs LOOP IF record.sal BETWEEN &low_sal AND &upp_sal THEN DBMS_OUTPUT.PUT_LINE(record.ename); END IF; END LOOP;END;
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CURSOR ATTRIBUTES
• %FOUND – Successful FETCH?• %NOTFOUND – Unsuccessful FETCH?• %ROWCOUNT – Processed number of rows• %ISOPEN – The cursor opened or not?
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USING CURSORS
ACCEPT low_sal PROMPT 'Lower bound! 'ACCEPT upp_sal PROMPT 'Upper bound! 'DECLARE CURSOR curs IS select * from emp; record EMP%ROWTYPE;BEGIN
OPEN curs;LOOP
FETCH curs INTO record;EXIT WHEN curs%NOTFOUND;IF record.sal BETWEEN &low_sal AND &upp_sal THEN
DBMS_OUTPUT.PUT_LINE(record.ename); END IF;END LOOP;CLOSE curs;
END; [email protected] 40
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USING CURSORS FOR MODIFICATIONS
CREATE TABLE worker AS …DECLARE
CURSOR curs IS SELECT * FROM workerFOR UPDATE [OF SAL] [NOWAIT];
record worker%ROWTYPE;mysal worker.sal%TYPE;
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BEGINOPEN cursor;LOOP
FETCH cursor INTO record;EXIT WHEN cursor%NOTFOUND;mysal := record.sal * 1.2;UPDATE worker set sal = mysal
WHERE CURRENT OF cursor; END LOOP;CLOSE cursor;
END;/
USING CURSORS FOR MODIFICATIONS
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SEARCHING FOR PAIRS• Aim: connect pair-records in a table using a calculation• The searching process is done by a PL/SQL script
program• This time: salary difference must be max 20%
• drop table worker;create table worker as select * from emp;alter table worker add pair number(4);update worker set pair=0;
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PAIRS• Principle: Using cursorA, we loop through the records
and for each record, we loop again through the records using cursorB
• The calculation is done with the current records of cursorA and cursorB
• Problem: how to identify records that already have pairs?
ROWID CLOSE+OPEN
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PAIRS
• Rowid: for every record, we use the ROWID or the primary key field to select the actual record from the table, thus we can check wether the pair field is set or not
• SELECT INTO, easier solution
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PAIRSSET SERVEROUTPUT ON
DECLARECURSOR curs_a IS select * from workers FOR UPDATE;CURSOR curs_b IS select * from workers FOR UPDATE;rec_a curs_a%ROWTYPE;rec_b curs_b%ROWTYPE;DIFF Numeric(5,2);
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PAIRS
BEGINOPEN curs_a;LOOP
FETCH curs_a INTO rec_a;EXIT WHEN curs_a%NOTFOUND;IF rec_a.pair=0 THEN
[searching for a pair]END IF;
END LOOP;CLOSE curs_a;
END;/
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PAIRS
OPEN curs_b;LOOP
FETCH curs_b INTO rec_b;EXIT WHEN curs_b%NOTFOUND;IF (rec_a.sal>rec_b.sal) THEN
Diff:=(rec_a.sal-rec_b.sal)/rec_a.sal; ELSE
Diff:=(rec_b.sal-rec_a.sal)/rec_b.sal; END IF;
IF rec_b.pair=0 AND Diff<0.1 AND rec_a.empno<>rec_b.empno THEN
[setting the pair]END IF;
END LOOP;CLOSE curs_b;
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PAIRS
DBMS_OUTPUT.PUT_LINE(rec_a.ename ||' ==> ' || rec_b.ename);
UPDATE workers SET pair=rec_a.empno WHERE CURRENT OF curs_b;UPDATE workers SET pair=rec_b.empno WHERE CURRENT OF curs_a;******EXIT;
***** CLOSE curs_a; OPEN curs_a;
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PAIRS
• Without Open+Close:
BLAKE ==> JONESJONES ==> FORDMARTIN ==> WARDALLEN ==> TURNERWARD ==> MILLERFORD ==> SCOTT
• With Open+Close:
BLAKE ==> JONESMARTIN ==> WARDALLEN ==> TURNERFORD ==> SCOTT
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DBMAN7
PL/SQL introductionControl StructuresExercisesCursorsExceptionsProcedures, TriggersTrigger exercise
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EXCEPTION HANDLING• In other languages: we can mark parts of code for
exception handling (try)• Cause an exception ourselves (throw)• We can do manual exception handling (catch, except)• In PL/SQL, exception handling is more automatic: no TRY
keyword• But we can throw/catch!
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PL/SQL BLOCK
• A separated area in the SQL*PLUS script-program, that is interpreted by the PL/SQL engine
• Syntax:SET SERVEROUTPUT ON[DECLARE {variables}]BEGIN
{commands}[EXCEPTION
{exception handling}]END;/
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USER-DEFINED EXCEPTIONSACCEPT var PROMPT "Write something! ";DECLARE MyEx EXCEPTION;BEGIN IF &var=0 THEN RAISE MyEx; END IF; DBMS_output.put_line('Not zero.');EXCEPTION WHEN MyEx THEN DBMS_output.put_line('Zero!');END;/
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AUTOMATIC EXCEPTIONS
When using SELECT INTO statement:– NO_DATA_FOUND– TOO_MANY_ROWS– OTHERS
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AUTOMATIC EXCEPTIONS
ACCEPT job PROMPT "Type in a job! ";DECLARE emprec EMP%ROWTYPE;BEGIN SELECT * INTO emprec FROM emp WHERE job='&job'; dbms_output.put_line(emprec.ename);EXCEPTION WHEN No_Data_Found THEN DBMS_output.put_line('No record!'); WHEN TOO_MANY_ROWS THEN DBMS_output.put_line('Too much
records!'); WHEN OTHERS THEN DBMS_output.put_line('Something else!');END;/
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DBMAN7
PL/SQL introductionControl StructuresExercisesCursorsExceptionsProcedures, TriggersTrigger exercise
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PROCEDURE• Parameters:
– {var.name} [{IN|OUT|IN OUT}] {type}– No size specification for types: VARCHAR2
• SHOW ERROR;(select * from user_errors)
• RAISE_APPLICATION_ERROR(err.code, message); [-20 999 .. -20 000]
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PROCEDURE
CREATE OR REPLACE PROCEDURE WriteItISBEGIN WriteLn('SzZs');END;/
select * from user_errors;
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PROCEDURECREATE OR REPLACE PROCEDURE WriteLn (text VARCHAR2)IS text2 VARCHAR2(50);BEGIN text2 := text; dbms_output.put_line(text2);END;/
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PROCEDURE
ACCEPT some PROMPT "Write something ";
BEGIN WriteIt; WriteLn('&valami');END;/
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EXECUTION / DELETION• Execution outside a PL-SQL block:
Execute WriteIt;Execute WriteLn('haha');
• Deletion: DROP PROCEDURE xxxxx;• DROP PROCEDURE WriteLn;
Execute WriteIt; Invalid object
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FUNCTIONCREATE OR REPLACE FUNCTION {name}
[ ({parameters}) ]RETURN {type}IS
[{local variablees}]BEGIN
{commands}[EXCEPTION …]END;/
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FUNCTION
CREATE OR REPLACE FUNCTION CountIt (num1 NUMBER, num2 NUMBER)
RETURN NUMBERIS c NUMBER(6); sum NUMBER(6);BEGIN sum := 0; FOR c IN num1 .. num2 LOOP sum := sum + c; END LOOP; RETURN sum;END;/
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FUNCTIONACCEPT first PROMPT "First num: ";ACCEPT second PROMPT "Second num: ";
BEGIN dbms_output.put_line(CountIt(&first, &second));END;/
DROP FUNCTION CountIt;
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TRIGGER?• trigger (n) = a piece (as a lever) connected with a catch
or detent as a means of releasing it; esp: the part of the action moved by the finger to fire a gun
• to trigger (v) = to initiate, actuate, or set off by sg "Event“
• In (Oracle) RDBMS: a stored procedure, that runs in connection with some event ("event handler")
• An event can be: DELETE, INSERT, UPDATE, CREATE, ALTER, DROP
• Important: BEFORE, AFTER, INSTEAD OF
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TRIGGER• Typical use: implementing a simple operation that can
be integrated with the database Client-independent operations
• E.g. logging, consistency-checking, subquery-dependent checks
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TRIGGERCREATE OR REPLACE TRIGGER {name}
[BEFORE | AFTER | INSTEAD OF]{event} [OR {event} …]ON {table}
[FOR EACH ROW [WHEN {condition}]][DECLARE {variables}]BEGIN
{commands}[EXCEPTION …]END;
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TRIGGER
• If there is a RAISE_APPLICATION_ERROR() in the trigger's code, then the event that caused the trigger will not be executed (+ automatic ROLLBACK)
• FOR EACH ROW: the trigger is executed once for each row modified/deleted/inserted. Otherwise: once for every command
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TRIGGER• When using a row-level trigger, we have several
automatically created variables:• INSERT - :NEW• DELETE - :OLD• UPDATE - :NEW and :OLD
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TRIGGERCREATE OR REPLACE TRIGGER SomeTriggerBEFORE DELETE OR INSERT OR UPDATE ON empFOR EACH ROWBEGIN IF INSERTING THEN DBMS_OUTPUT.PUT_LINE(NEW: ' || :NEW.ename); ELSIF DELETING THEN DBMS_OUTPUT.PUT_LINE(DEL: ' || :OLD.ename); ELSIF UPDATING THEN DBMS_OUTPUT.PUT_LINE(MOD: ' || :OLD.ename || ' ==> '
|| :NEW.ename); END IF;END;/
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TRIGGER
delete from emp where ename='KING';update emp set ename='SOME' where
ename='JAMES';insert into emp (empno, ename, mgr, deptno) values
(1, 'NEWMAN', NULL, 20);
DEL: KING1 row deleted.MOD: JAMES ==> SOME1 row updated.NEW: NEWMAN
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TRIGGER
CREATE OR REPLACE TRIGGER SomeTrigger2BEFORE INSERT ON empFOR EACH ROWDECLARE
MINSAL NUMERIC(6,2);BEGIN SELECT MIN(SAL) INTO MINSAL FROM EMP; IF (:NEW.sal < MINSAL) THEN RAISE_APPLICATION_ERROR(-20000, 'TOO LOW SALARY!'); END IF;END;/
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TRIGGERinsert into emp (empno, ename, mgr, deptno, sal) values
(4, 'NEWMAN2', NULL, 20, 5000);insert into emp (empno, ename, mgr, deptno, sal) values
(5, 'NEWMAN3', NULL, 20, 5);delete from emp where empno < 100;
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TRIGGER
UJ: NEWMAN21 row created.insert into emp (empno, ename, mgr, deptno, sal)
values (5, 'NEWMAN3', NULL, 20, 5) *ERROR at line 1:ORA-20000: TOO LOW SALARY!ORA-06512: at "SCOTT.SOMETRIGGER2", line 6ORA-04088: error during execution of trigger
'SCOTT.SOMETRIGGER2'DEL: NEWMANDEL: NEWMAN22 rows deleted.
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TABLE-LEVEL TRIGGER
CREATE OR REPLACE TRIGGER SomeTrigger2BEFORE DELETE OR INSERT OR UPDATE ON empBEGIN IF INSERTING THEN DBMS_OUTPUT.PUT_LINE('NEW REC'); ELSIF DELETING THEN DBMS_OUTPUT.PUT_LINE('DELETED REC'); ELSIF UPDATING THEN DBMS_OUTPUT.PUT_LINE('MODDED REC'); END IF;END;/
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THINGS TO REMEMBER…• A table-level trigger will be executed once even if
affected_rows=0!• INSTEAD OF: row-level trigger (even without FOR EACH
ROW!), used with views• WHEN: we can define conditions for row-level triggers
using the :NEW and the :OLD variables• DROP TRIGGER xxxx;• ALTER TRIGGER xxxx ENABLE/DISABLE;
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DBMAN7
PL/SQL introductionControl StructuresExercisesCursorsExceptionsProcedures, TriggersTrigger exercise
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10.5• Must forbid the insertion of workers who don't apply to
some rules• The condition-checks are done by separated functions!• The trigger does nothing complicated: it calls the
appropriate functions, and raises an exception if the record is considered bad
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A TYPICAL TRIGGER
create or replace trigger Checks before insert on xxxxxxxxxxxfor each rowDECLARE
Ex1 Exception;Ex2 Exception;
BEGINif (F1(:NEW.field)<>1) then Raise Ex1; end if;if (F2(:NEW.field1, :NEW.field2)<>1) then Raise Ex2; end if;
EXCEPTIONWHEN Ex1 THEN Raise_Application_Error(-20500, 'Error1');WHEN Ex2 THEN Raise_Application_Error(-20501, 'Error2');WHEN OTHERS THEN Raise_Application_Error(-20999, 'Error');
END;/
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Rules create table dx as select * from emp;1) The mgr field must point to an already existing boss2) No boss can have more than two employees3) The job must be an already existing job4) The department must be an existing department
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FUNCTION 1create or replace function Check_Boss(id int)return intIS
temp int;BEGIN
if id is null then return 0; end if;select distinct mgr into temp from emp where mgr=id;return 1;
EXCEPTIONWHEN NO_DATA_FOUND THEN return 0;WHEN OTHERS THEN return 0;
END;/select * from user_errors;
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FUNCTION 1create or replace function Check_Boss(id int)return intIS
temp int;BEGIN
if id is null then return 0; end if;select count(*) into temp from emp where mgr=id;if temp>0 then
return 1;else
return 0;end if;
EXCEPTIONWHEN OTHERS THEN return 0;
END;/select * from user_errors;
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THE TRIGGERcreate or replace trigger Checksbefore insert on dxfor each rowDECLARE
NonExistingBoss Exception;BEGIN
if (Check_Boss(:NEW.mgr)<>1) then Raise NonExistingBoss; end if;EXCEPTION
WHEN NonExistingBoss THEN Raise_Application_Error(-20500, ‘The boss does not exist!');WHEN OTHERS THEN Raise_Application_Error(-20999, ‘ERROR');
END;/
insert into dx (empno, sal, mgr, job, deptno) values (10, 500, 5, 'CLERK', 20);
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FUNCTION 2create or replace function Check_Workers(id int)return intIS
temp int;BEGIN
select count(*) into temp from emp where mgr=id;if temp<2 then
return 1;else
return 0;end if;
EXCEPTIONWHEN OTHERS THEN return 0;
END;/select * from user_errors;
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FUNCTION 3create or replace function Check_Job(job_param varchar2)return intIS
temp int;BEGIN
select count(*) into temp from emp where job=job_param;if temp>0 then
return 1;else
return 0;end if;
EXCEPTIONWHEN OTHERS THEN return 0;
END;/select * from user_errors;
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FUNCTION 4create or replace function Check_Dept(dept_param int)return intIS
temp int;BEGIN
select count(*) into temp from dept where deptno=dept_param;if temp>0 then
return 1;else
return 0;end if;
EXCEPTIONWHEN OTHERS THEN return 0;
END;/select * from user_errors;
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DECLAREBad_Boss Exception;Bad_Workers Exception;Bad_Job Exception;Bad_Dept Exception;
BEGINif (Check_Boss(:NEW.mgr)<>1) then Raise Bad_Boss; end if;if (Check_Workers(:NEW.mgr)<>1) then Raise Bad_Workers; end if;if (Check_Job(:NEW.job)<>1) then Raise Bad_Job; end if;if (Check_Dept(:NEW.deptno)<>1) then Raise Bad_Dept; end if;
EXCEPTIONWHEN Bad_Boss THEN Raise_Application_Error(-20500, ‘Nonexistant boss');WHEN Bad_Workers THEN Raise_Application_Error(-20501, ‘Too many sub-employees!');WHEN Bad_Job THEN Raise_Application_Error(-20502, ‘Nonexistant job');WHEN Bad_Dept THEN Raise_Application_Error(-20503, ‘Nonexistant department');WHEN OTHERS THEN Raise_Application_Error(-20999, ‘Unknown error');
END;/
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TESTING• Nonexistant boss:
– insert into dx (empno, sal, mgr, job, deptno) values (10, 500, 5, 'CLERK', 20);
• Too much sub-employees:– insert into dx (empno, sal, mgr, job, deptno) values
(10, 500, 7698, 'CLERK', 20);• Nonexistant job:
– insert into dx (empno, sal, mgr, job, deptno) values (10, 500, 7788, 'BAKER', 20);
• Nonexistant department:– insert into dx (empno, sal, mgr, job, deptno) values
(10, 500, 7788, 'CLERK', 70);
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Rules5) The salary must be lower than the average salary of
the department6) The salary must be higher than the minimum salary in
the given job
• We add the functions to the trigger code• We test the functionality of the trigger
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