General Note: Here we have pulled in the data from a sample database. You can download it from the following link and use it for practicing Click Here For Sample Database
Left outer join does the same work as inner join but has very minor difference. The "left outer join" joins two table and retrieves data from both table like inner join, but if there is no matching data in left table, it will return those left table data also in the result. Just modifying the same inner join query with left outer join.
However, this query will not make any difference. Because both table have same mobile names.
Select m1.mobile_name, price, brand_name, star5 from mobile_sales_details m1 left outer join mobile_rating m2 on m1.mobile_name=m2.mobile_name
So we are inserting some data to location table using the insert query. Copy and execute the below two query in your editor.
insert into company_location values(11,'Malasiya') insert into company_location values(10,'Poland')
Now these two location are added in location table. Now we are writing left outer join for company location table with brand_details. It will return Malasiya and Poland in the result. Because of left outer join, it will return the unmatched data in left table.
If you change the left table to right the result will change.
select t1.location_id,t2.location_id,country_name from company_location t1 left outer join brand_details t2 on t1.location_id=t2.location_id
location_id location_id country_name ----------- ----------- ------------ 1 1 Finland 2 2 United State 2 2 United State 2 2 United State 2 2 United State 2 2 United State 3 3 Taiwan 3 3 Taiwan 4 4 France 5 5 South Korea 6 6 Japan 7 7 India 7 7 India 7 7 India 7 7 India 8 8 China 9 9 Canada The two null values represents the concept of left outer join