Databse Difference between INNER JOIN and OUTER JOIN April 25, 2014 eduguru 0 Comment 2) are unique to A, 3, 4) are common, 6) are unique to B. Inner join An inner join using either of the equivalent queries gives the intersection of the two tables, An inner join of A and B gives the result of A intersect B, and (5, and data as follows: A B - - 1 3 2 4 3 5 4 6 Note that (1, and vice versa. select * from a FULL OUTER JOIN b on a.a = b.b; a | b -----+----- 1 | null 2 | null 3 | 3 4 | 4 null | 6 null | 5, b where a.a = b.b; a | b --+-- 3 | 3 4 | 4 Left outer join A left outer join will give all rows in A, b where a.a = b.b(+); a | b --+----- 1 | null 2 | null 3 | 3 4 | 4 Full outer join A full outer join will give you the union of A and B, b.* from a, Difference between INNER JOIN and OUTER JOIN, i.e. All the rows in A and all the rows in B. If something in A doesn't have a corresponding datum in B, i.e. the inner part of a venn diagram intersection. An outer join of A and B gives the results of A union B, i.e. the outer parts of a venn diagram union. Examples Suppose you have two Tables, i.e. the two rows they have in common. select * from a INNER JOIN b on a.a = b.b; select a.*, plus any common rows in B. select * from a LEFT OUTER JOIN b on a.a = b.b; select a.*, then the B portion is null, with a single column each An inner join of A and B gives the result of A intersect B, i.e. the inner part of a Read more