Syntax:
SHOW WARNINGS [LIMIT [offset,] row_count]
SHOW COUNT(*) WARNINGS

SHOW WARNINGS is a diagnostic statement that displays information about
the conditions (errors, warnings, and notes) resulting from executing a
statement in the current session. Warnings are generated for DML
statements such as INSERT, UPDATE, and LOAD DATA INFILE as well as DDL
statements such as CREATE TABLE and ALTER TABLE.

The LIMIT clause has the same syntax as for the SELECT statement. See
http://dev.mysql.com/doc/refman/5.5/en/select.html.

SHOW WARNINGS is also used following EXPLAIN EXTENDED, to display the
extra information generated by EXPLAIN when the EXTENDED keyword is
used. See http://dev.mysql.com/doc/refman/5.5/en/explain-extended.html.

SHOW WARNINGS displays information about the conditions resulting from
the most recent statement in the current session that generated
messages. It shows nothing if the most recent statement used a table
and generated no messages. (That is, statements that use a table but
generate no messages clear the message list.) Statements that do not
use tables and do not generate messages have no effect on the message
list.

The SHOW COUNT(*) WARNINGS diagnostic statement displays the total
number of errors, warnings, and notes. You can also retrieve this
number from the warning_count system variable:

SHOW COUNT(*) WARNINGS;
SELECT @@warning_count;

A related diagnostic statement, SHOW ERRORS, shows only error
conditions (it excludes warnings and notes), and SHOW COUNT(*) ERRORS
statement displays the total number of errors. See [HELP SHOW ERRORS].

URL: http://dev.mysql.com/doc/refman/5.5/en/show-warnings.html

