When you create a database, you normalize the data by placing information specific to different objects in different tables, rather than in one large table with many redundant entries.
A join operation recreates a larger table using the information from two or more tables (or views). Using different joins, you can construct a variety of these virtual tables, each suited to a particular task.
This chapter assumes some knowledge of queries and the syntax of the select statement. Information about queries appears in Queries: Selecting Data from a Table.
Sample database schema
How joins work
Joins overview
Explicit join conditions (the ON phrase)
Cross joins
Inner and outer joins
Specialized joins
Natural joins
Key joins