Sometimes you can specify the same set of rows using either a WHERE clause or a HAVING clause. In such cases, one method is not more or less efficient than the other. The optimizer always automatically analyzes each statement you enter and selects an efficient means of executing it. It is best to use the syntax that most clearly describes the intended result. In general, that means eliminating undesired rows in earlier clauses.
Discuss this page in DocCommentXchange.
|Copyright © 2014, SAP AG or an SAP affiliate company. - SAP Sybase SQL Anywhere 16.0|