Previous Topic: DescriptionNext Topic: Example 1

SQL Statements › UPDATE › Positioned UPDATE › Processing

Processing

Update values are assigned to columns in accordance with the following assignment rules:

If update value is:

The column must be:

A number

A numeric column with the capacity to represent the integral part of the number

A character string

A character string column with a length attribute that is not less than the length of the string

The updated row must conform to any constraint imposed on the table (or on the base table of the view) by any unique index on an update column. If an update value violates any of those constraints, or if any other error occurs during the execution of the UPDATE statement, no rows are updated. If an error occurs during the execution of UPDATE that makes the position of a cursor unpredictable, the cursor is closed. Rows can be changed so that they no longer conform to the definition of the view. Such rows are updated in the base table of the view and no longer appear in the view.

Unless appropriate locks already exist, one or more exclusive locks are acquired by the execution of a successful UPDATE statement. Until the locks are released, an updated row can be accessed only by the unit of recovery that performed the update.