table of Contents
Cross-connect (cross join)
Without any connection conditions, which can not any relationship between the table and the table, which is a Cartesian product of the execution result, corresponding to m * n;
The connector (inner join)
inner keyword can be omitted.
Query only match the query, and the join condition line, eliminating any line to another table does not match.
Outer join
Left (outer) connector, left (outer) join, the extra data will be displayed in the left table;
Right (outer) connector, right (outer) join, the extra data will be displayed in the right table;
Full (outer) connector, full (outer) join, the extra data will be two tables are displayed.
Several connections can be used with.