This allows setting a transaction isolation in a stored procedure or trigger body. The values are:

These are case insensitive strings.

This takes effect dynamically until replaced by another SET ISOLATION setting. The effect never persists over the return of the containing procedure or trigger. The effect does extend into procedures or triggers called from after executing the SET ISOLATION statement.

set isolation='serializable';

The initial isolation comes from the SQL_TXN_ISOLATION statement option in the ODBC API (SQLSetConnectOption). The default isolation is repeatable read.