Read this SQL tutorial to learn when to use SELECT, JOIN, subselects and UNION to access multiple tables with a single statement.

In this sample statement, the condition (table1.keyfield=table2.keyfield) tells SQL to find records in both tables that contain matching values in the column named by keyfield.

How to Reindex SQL Tables. The indexes on a the tables of a large database make a huge difference in its performance and utility. Without an index, locating a single record in a large table can ...