First off: there is no need to. A read-only cursor would do just fine on a PHP. On a PHP-script it is impossible to update any data via a open cursor.

This would avoid the infamous
SL002: Positioned request could not be performed because result set was created by a join condition.

The error can be reproduced by simply executing a SQL-clause with a join in it on a MS SQL 7.x or greater. Joins on a MS SQL (or Sybase) are not updateable so a read-only cursor is required.

Also it would be nice to warn users that odbc_fetch_into
cannot be used to retrieve any data selected with a join.