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Chapter 1 : writting Basic select statement:--------------------------------------------username : scottpassword : tiger

part I : how to wirte select statement---------------------------------------syntax......select select_listfrom table_name ;

1.1 ) selecting certain columns-------------------------------select empno , ename , sal , deptnofrom emp ;

1.2) selecting all columns--------------------------select *from emp ;

1.3) to display tables in current user--------------------------------------

select *from tab ;

Desc emp

1.4) writting expressions--------------------------select empno , ename, sal , sal + 100from emp

select empno , ename, sal , sal + 100 * 5from emp

select empno , ename, sal , (sal + 100) *5from emp ;

select empno , ename, sal , sal / 100 * 5from emp ;

1.5) using alias----------------

select empno , ename, sal , (sal + 100)*5from emp ;

select empno , ename, sal , (sal + 100)*5 as "New Salary"

from emp ;

select empno , ename, sal , (sal + 100)*5 as New_Salaryfrom emp ;

select empno , ename, sal salary , (sal + 100)*5 as "New Salary"from emp ;

1.6) concatenation operator:

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----------------------------

select empno , ename, job , ename || jobfrom emp ;

select ' Employee No. ' || empno || ' his name is ' || ename ||' works as ' || jobfrom emp;

1.7) supress duplication in rows---------------------------------

select distinct jobfrom emp ;

select distinct deptno , jobfrom emp ;

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Part II) : Restricting Data :----------------------------Syntax:-------

select select_listfrom table_namewhere condition

Condition = column_name operator valuesal > 1000

deptno = 10 ename = 'SCOTT'Examples--------2.1 ) using comparisone operators:----------------------------------select *

from empwhere deptno = 30;

select *from empwhere sal > 1500 ;

select *from empwhere ename ='SCOTT' ;

Operators : = > < >=

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where sal between 1000 and 3000 ;...................................................................................

2.4) like operator------------------select *from empwhere ename like 'A%' ;

select *from empwhere ename like '%R' ;

select *from empwhere ename like '%L%' ;

select *from empwhere ename like '%L%L%' ;

select *from emp

where ename like '_A%' ;

select *from empwhere ename like '__A%' ;

select *from empwhere ename like '%E_' ;

2.5) null values:-----------------select *

from empwhere comm is null

select *from empwhere comm is not null

2.6) more than one condition----------------------------and----select *from emp

where deptno = 30 and sal > 1500 ;

OR--select *from empwhere deptno = 30 or sal > 1500 ;

Logic Tables------------

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OR true false nulltrue t t tfalse t f nnull t n n

and true false null

true t f nfalse f f fnull n f n

NOT---select *from empwhere sal not between 1000 and 2000 ;

select *from empwhere job not in ( 'ANALYST' , 'SALESMAN') ;

select *from empwhere ename not like 'A%' ;

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Part III : Sorting Data-----------------------Syntax :--------select select_listfrom table_nameorder by order_by_list ;

Examples :

----------select * from emp order by sal ;select * from emp order by sal desc ;

select empno , ename , deptno , sal from emp order by deptno , sal ;

select empno , ename , deptno , salfrom emporder by deptno , sal desc ;

select empno , ename , deptno , sal from emp order by 3 , 4 ;

select empno , ename , sal salary from emp order by salary ;

//////////////////////////////Chapter END//////////////////////////////////////

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