Feb 12 2020.txt

select * from emp;
-- null treatment
-- with null, we can't perform any type task (arithmetic ,boolean)

select 10+10 from dual;
select 10-10 from dual;
select 10+null from dual;

select 'jitendra' from dual;

select 'oracle';

select 'oracle' from ;

select 'oracle',10+2 from emp;

select oracles from emp;

select * from naveen;

select naveen from emp;
select * from dual;

select 'X','Y','Z' from dual
union all
select 'X','Y','Z' from dual
union all
select 'X','Y','Z' from dual
union all
select 'X','Y','Z' from dual;

-- null value 
select null + 10 from dual;
select 10/0 from dual;
select null/0 from dual;

-- beelean operator

select * from emp where deptno=null;

select * from emp where deptno>null;

select * from emp where 1=1;

select * from emp where null=null;

select * from emp;

select deptno from emp;

select * from emp where comm=0;

select * from emp where comm>0;

select * from emp where comm=null; -- is (special operator)

select * from emp where comm is null;

select * from emp where comm is not null;

select * from emp where ename is null;

select * from emp where ename not like 'A%';

select * from emp where job='ANALYST' and sal=3000;

select * from emp where job='ANALYST' or sal=3000;

select ename,sal from emp where job='ANALYST' or sal=3000;


-- Testing
-- 

create table demo_char_varchar_01
(
name1 char(10),
name2 varchar(10));

insert into demo_char_varchar_01 values('Oracle','Oracle');

select length(name1),name1,length(name2),name2 from demo_char_varchar_01;

insert into demo_char_varchar_01 values('O','O');