Security update mode for MySQL

The following error was reported when deleting data from a table in MySQL:

mysql> delete from upload_images;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column


mysql> show variables like '%sql_safe%';
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| sql_safe_updates | ON |
+------------------+-------+
1 row in set (0.00 sec)

mysql> set sql_safe_updates=0;

Query OK, 0 rows affected (0.00 sec)

mysql> show variables like '%sql_safe%';
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| sql_safe_updates | OFF |
+------------------+-------+
1 row in set (0.00 sec)
mysql> delete from upload_images;
Query OK, 505 rows affected (0.01 sec)

And then enable Safe mode.

Mysql> set Sql_safe_updates=1;