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Full Outer Join in PostgreSQL

Full Outer Join:
The Full Outer Join query after joining returns all the records from the selected fields of both the tables irrespective of the fact that the join condition is met or not.

Syntax:

SELECT expr_1, expr_2, ... expr_n  
FROM table_1   
FULL OUTER JOIN table_2  
ON join_predicate;

Parameters:
join_predicate: It is used to specify the joining conditions to be strictly followed for joining.

Example:
Employment Table:

ID	STATE	RATE
1	A	60
2	B	70
3	C	65
4	D	80
5	E	78

Department Table:

ID	NAME	PERCENT
1	IT	60
2	Sales	75
3	Bank	50

Query:

SELECT “EMPLOYMENT”.“ID”, “EMPLOYMENT”.“STATE”, “DEPARTMENT”.“NAME”  
FROM “EMPLOYMENT”   
FULL OUTER JOIN “DEPARTMENT”  
ON “EMPLOYMENT”.“ID” = “DEPARTMENT”.“ID”;

Output:

ID	STATE	NAME
1	A	IT
2	B	Sales
3	C	Bank
4	D	
5	E	

Explanation:
The EMPLOYMENT and the DEPARTMENT are the already existing tables that are joined with FULL OUTER JOIN query so that all the records from the EMPLOYMENT table and the DEPARTMENT table for the selected fields is combined in the result set.

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