[PGS9.2] Usage of JOIN ~ USING()

/********************************************************************************************
-- Title : [PGS9.2] Usage of JOIN ~ USING()
-- Reference : dbrang.tistory.com
-- Key word : postgresql join using 조인
********************************************************************************************/

-- Initiate Table

drop table ttt_1;

drop table ttt_2;

 

-- Create Table

create table ttt_1

( a int

, b int

);

 

create table ttt_2

( a int

, c int

);

 

-- Insert Data

insert into ttt_1 values (1,1);

insert into ttt_1 values (2,2);

insert into ttt_1 values (3,3);

insert into ttt_1 values (4,4);

insert into ttt_1 values (5,5);

 

insert into ttt_2 values (2,22);

insert into ttt_2 values (3,33);

insert into ttt_2 values (4,44);

insert into ttt_2 values (5,55);

insert into ttt_2 values (6,66);

 

-- Select Table

select *

from ttt_1 a

full outer join ttt_2 b

on a.a = b.a;

 

-- Select Join with INNER_USING()

-- Not print duplicate matched column in ON clause.

select *

from ttt_1 a

inner join ttt_2 b USING(a);

 a | b | c

---+---+----

 2 | 2 | 22

 3 | 3 | 33

 4 | 4 | 44

 5 | 5 | 55

 

-- Select Join with INNER~ON

-- Print duplicate matched column in ON clause.

select *

from ttt_1 a

inner join ttt_2 b 

on a.a = b.a;

 a | b | a | c

---+---+---+----

 2 | 2 | 2 | 22

 3 | 3 | 3 | 33

 4 | 4 | 4 | 44

 5 | 5 | 5 | 55