SHOW WARNINGS
该语句显示在当前客户端连接中之前执行的语句所发生的警告列表。与 MySQL 一样，sql_mode 会显著影响哪些语句会引发错误与警告。
概述
- ShowWarningsStmt
ShowWarningsStmt ::=
"SHOW" "WARNINGS"
示例
mysql> CREATE TABLE t1 (a INT UNSIGNED);
Query OK, 0 rows affected (0.11 sec)
mysql> INSERT INTO t1 VALUES (0);
Query OK, 1 row affected (0.02 sec)
mysql> SELECT 1/a FROM t1;
+------+
| 1/a |
+------+
| NULL |
+------+
1 row in set, 1 warning (0.00 sec)
mysql> SHOW WARNINGS;
+---------+------+---------------+
| Level | Code | Message |
+---------+------+---------------+
| Warning | 1365 | Division by 0 |
+---------+------+---------------+
1 row in set (0.00 sec)
mysql> INSERT INTO t1 VALUES (-1);
ERROR 1264 (22003): Out of range value for column 'a' at row 1
mysql> SELECT * FROM t1;
+------+
| a |
+------+
| 0 |
+------+
1 row in set (0.00 sec)
mysql> SET sql_mode='';
Query OK, 0 rows affected (0.00 sec)
mysql> INSERT INTO t1 VALUES (-1);
Query OK, 1 row affected, 1 warning (0.01 sec)
mysql> SHOW WARNINGS;
+---------+------+---------------------------+
| Level | Code | Message |
+---------+------+---------------------------+
| Warning | 1690 | constant -1 overflows int |
+---------+------+---------------------------+
1 row in set (0.00 sec)
mysql> SELECT * FROM t1;
+------+
| a |
+------+
| 0 |
| 0 |
+------+
2 rows in set (0.00 sec)
MySQL 兼容性
TiDB 中的 SHOW WARNINGS 语句与 MySQL 完全兼容。如果你发现任何兼容性差异，请报告一个 bug。