When executing multi-row operations, what should be the first thing you look for to see if anything unexpected happened?

When executing multi-row operations, what should be the first thing you look for to see if anything unexpected happened?

A.
Warning/Error Count.

B.
Warning/Error Codes.

C.
Warning/Error messages.

Explanation:
Query OK, 3 rows affected, 3 warnings (0.08 sec) Records: 3 Duplicates: 0 Warnings: 3. See Count, then SHOW WARNINGS if exist.