Left Join in DBMS

Three points  about left outer join

1. Tables are join based on some condition.
2. Only matched records from right side table and all records from the left side table  are displayed.
3. The result is Null if there is no match from the right side table.

Syntax:

select col1,col2,col3.... 
from

LEFT JOIN on.common_column =.common_column;

Left Join Example

Consider two tables  emp and dept tables

Emp table

Dept table

Left Join SQL query

select rownum,Empno,Ename,Emp.Deptno,Dname, sal*12 annsal,loc,job
from 
Emp
LEFT JOIN
Dept
on Emp.Deptno=Dept.deptno and dname='SALES';

O/P

There are 6 matched records with deptno=30 and dname =’SALES’ from dept table with emp table and 9 records in emp table that are unmatched in that case if there is no data to be appended  from right side table null values are placed hence total 14 rows are displayed.