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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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