The Microsoft ODBC Programmer's Reference suggests that you use SELECT...FOR UPDATE to indicate that a query is updatable using positioned operations. You do not need to use the FOR UPDATE clause in SQL Anywhere: SELECT statements are automatically updatable as long as the following conditions are met:
The underlying query supports updates.
That is to say, as long as a data manipulation statement on the columns in the result is meaningful, then positioned data manipulation statements can be carried out on the cursor.
The ansi_update_constraints database option limits the type of queries that are updatable.
The cursor type supports updates.
If you are using a read-only cursor, you cannot update the result set.
ODBC provides two alternatives for carrying out positioned updates and deletes:
Use the SQLSetPos function.
Depending on the parameters supplied (SQL_POSITION, SQL_REFRESH, SQL_UPDATE, SQL_DELETE) SQLSetPos sets the cursor position and allows an application to refresh data, or update, or delete data in the result set.
This is the method to use with SQL Anywhere.
Send positioned UPDATE and DELETE statements using SQLExecute. This method should not be used with SQL Anywhere.
Discuss this page in DocCommentXchange.
|Copyright © 2012, iAnywhere Solutions, Inc. - SQL Anywhere 12.0.1|