When the INSERT statement fails with the error code specified in the DECLARE exit handler statement, control passes to the handler, and the procedure is exited.
Listing 12 shows a handler that will exit the procedure when SQL warnings and the not found conditions are encountered.
清单12展示了一个处理程序，它将在遇到SQL警告和not found条件时退出过程。
3
Since a procedure in a high-level language has a single entry and a single exit point, it is common for a CFG to have a unique entry and exit node as well.