The difference between SQL left link, right link, and full link

Outer joins: Left outer connection, right outer connection, full outer connection
Left outer connection is to left table, to match the right table, the left table has how many data, the result is how many data
SELECT * from A LEFT join B on A.id=b.id
ID      name            ID      
1          a                1       
2          b                null      NULL
4          c                null      NULL
The right outer connection is connected with the left outer connection, in contrast, to the right table, to match the left table, the right table has how many data, the result is how many data
SELECT * from A right join B on A.id=b.id
ID      name            ID      
1          a                1       
Null        NULL               3       C
Total outer JOIN Data bar number is not necessarily, quite with is the left outer connection and the right outer joins the synthesis
SELECT * from A full join B on A.id=b.id
ID      name            ID      
1          a                1       
2          b                null      NULL
Null       NULL               3       C
4          c                 null       NULL

The difference between SQL left link, right link, and full link