Computed column values are automatically maintained by the database server as rows are inserted and updated. Most applications should never need to update or insert computed column values directly.
Computed columns are recalculated under the following circumstances:
Any column is deleted, added, or renamed.
The table is changed by an ALTER TABLE statement that modifies any column's data type or COMPUTE clause.
A row is inserted.
A row is updated.
Computed columns are not recalculated under the following circumstances:
The table is renamed.
The computed column is queried.
The computed column depends on the values of other rows (using a subquery or user-defined function), and these rows are changed.
Discuter à propos de cette page dans DocCommentXchange.
|Copyright © 2013, SAP AG ou société affiliée SAP - SAP Sybase SQL Anywhere 16.0|