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. Therefore, to retrieve related data from more than one table, you perform a join operation using the SQL JOIN operator. 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.
Discuter à propos de cette page dans DocCommentXchange.
|Copyright © 2012, iAnywhere Solutions, Inc. - SQL Anywhere 12.0.1|