joins
Joins in SQL
One of the most powerful features of SQL is its capability to gather and manipulate data from across several tables. Without this feature we would have to store all the data elements necessary for each application in one table. Without common tables we would need to store the same data in several tables. Imagine having to redesign, rebuild, and repopulate our tables and databases every time our user needed a query with a new piece of information. The JOIN statement of SQL enables us to design smaller, more specific tables that are easier to maintain than larger tables.