A SELECT statement can reference data in two or more tables and the relational join combines the data from the referenced tables.
In this way, the SELECT statement defines a join of specified tables to retrieve data more efficiently than without defining a join of tables.
There are two kinds of joins:
Join | Description |
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Inner | Selects data from two or more tables that meet specific join conditions. Join condition (common relationship among the tables to join) can be on ON clause or WHERE clause. |
Outer | Extension of the inner join that includes the following:
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