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IntroductionIf you're new to SQL or just new to Oracle SQL, perhaps coming from a Microsoft SQL Server environment, it may seem like the two versions should be very similar, and they are, to a certain degree, but they are also very different in some important and basic ways.

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AgendaI. Quick Intro for SQL Server UsersII. Some Detail: Joins, Subqueries, DeletesIII. Certain Conceptual DifferencesIV. Powerful New FeaturesV. Summary & References

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Don’t Use DatabasesSQL Server

use mydatabase

Oracle

connect mydatabase/mypassword

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Use DualSQL Server

Oracle

select getdate();

select sysdate from dual;

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Select IntoSQL Server

Oracle

select getdate() mycolumn into mytable;

insert into mytable (mycolumn)

values(sysdate);

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InsertsSQL Server

Oracle

Insert mytable values(‘more text’);

Insert into mytable values(‘more text’);

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UpdatesSQL Server

update mytable set mycolumn=myothertable.mycolumn from mytable,myothertable where mytable.mycolumn like 'MY%'

and myothertable.myothercolumn='some text';

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UpdatesOracleupdate mytableset mycolumn=(select a.mycolumn from myothertable a where myothertable.myothercolumn='some text';)

where mytable.mycolumn like 'MY%';

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DeletesSQL Server

delete mytable where mycolumn like 'some%';

Oracle

delete from mytable

where mycolumn like 'some%';

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Software

• isql

• osql: for queries developed in SQL Analyzer

• sqlplus

SQL Server

Oracle

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II. A Little More DetailOuter JoinSub-Queries in Place of ColumnsDeletes With a Second From Clause

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Outer JoinSQL Server select d.deptname, e.ename from dept d,

emp e where d.empno *= e.enum;Oracle select d.deptname,e.ename from dept d,

emp e where d.empno = e.enum (+);

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SubQueries in Place of ColumnsSQL Server

select distinct year,q1 = (select Amount amt FROM saleswhere Quarter=1 AND year = s.year),q2 = (SELECT Amount amt FROM saleswhere Quarter=2 AND year = s.year),q3 = (SELECT Amount amt FROM saleswhere Quarter=3 AND year = s.year),q4 = (SELECT Amount amt FROM saleswhere Quarter=4 AND year = s.year)

from sales s;

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SubQueries in Place of ColumnsOracle

SELECT year,

DECODE( quarter, 1, amount, 0 ) q1,

DECODE( quarter, 2, amount, 0 ) q2,

DECODE( quarter, 3, amount, 0 ) q3,

DECODE( quarter, 4, amount, 0 ) q4

FROM sales s;

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Delete with Second From ClauseSQL Server

delete

from products

from products, product_deletes

where products.a = product_deletes.a

and products.b = product_deletes.b

and product_deletes.c = 'd';

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Delete with Second From Clause

Oracle

deletefrom productswhere ( a, b ) in( select a, bfrom product_deleteswhere c = 'd' );

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III. More DepthThe Connect ConceptOther Conceptual DifferencesData Type DifferencesColumn AliasesSub-Queries

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The Connect ConceptSQL Server Multiple databasesOracle Single Database Multiple tablespaces, schemas, users

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Other Conceptual DifferencesSQL ServerDatabase owner, DBOGroup/RoleNon-unique indexT-SQL stored procedure {TriggerCompex ruleColumn identity property

OracleSchemaRoleIndexPL/SQL procedurePL/SQL functionBEFORE triggerAfter triggerSequence

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Only in OracleClustersPackagesTriggers for each rowSynonymsSnapshots

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Data Type DifferencesSQL Server OracleINTEGER NUMBER(10)

SMALLINT NUMBER(6)

TINYINT NUMBER(3)

REAL FLOAT

FLOAT FLOAT

BIT NUMBER(1)

VARCHAR(n) VARCHAR2(n)

TEXT CLOB

IMAGE BLOB

BINARY(n) RAW(n) or BLOB

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Data Type DifferencesSQL Server OracleVARBINARY RAW(n) or BLOBDATETIME DATESMALL-DATETIME DATEMONEY NUMBER(19,4)NCHAR(n) CHAR(n*2)NVARCHAR(n) VARCHAR(n*2)SMALLMONEY NUMBER(10,4)TIMESTAMP NUMBERSYSNAME VARCHAR2(30), VARCHAR2(128)

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TimeSQL Server Datetime: 1/300th secondOracle Date: 1 second Timestamp: 1/100 millionth second

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Column AliasesSQL Server select a=deptid, b=deptname,c=empno

from dept;Oracle select deptid a, deptname b, empno c from

dept;

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Sub-queries, againSQL Server

SELECT ename, deptnameFROM emp, deptWHERE emp.enum = 10AND(SELECT security_codeFROM employee_securityWHERE empno = emp.enum) =

(SELECT security_codeFROM security_master

WHERE sec_level = dept.sec_level);

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Sub-queries, againOracle

SELECT empname, deptnameFROM emp, deptWHERE emp.empno = 10AND EXISTS (SELECT security_codeFROM employee_security esWHERE es.empno = emp.empnoAND es.security_code =

(SELECT security_codeFROM security_masterWHERE sec_level = dept.sec_level));

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Powerful New FeaturesRegular Expressions: Operators & FunctionsOperator: REGEXP_LIKEFunctions: REGEXP_INSTR REGEXP_SUBSTR REGEXP_REPLACE

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Regular ExpressionsSelect zip from zipcode where regexp_like (zip, ‘[^[:digit:]]’);

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Regular ExpressionsSELECT REGEXP_INSTR('Joe Smith,

10045 Berry Lane, San Joseph, CA 91234-1234',

' [[:digit:]]{5}(-[[:digit:]]{4})?$')

AS starts_at

FROM dual

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