mysql查询类型转换_MySQL

mysql查询类型转换

在mysql查询时最好不要发生类型转换,如把varchar转换成int

mysql> explain select * from user where name=1/G

//如果你确定name字段是整型就不要把它转化成字符串,不加单引号

*************************** 1. row ***************************           id: 1  select_type: SIMPLE        table: user         type: ALLpossible_keys: index_name_password          key: NULL      key_len: NULL          ref: NULL         rows: 99727        Extra: Using where1 row in set (0.02 sec)mysql> explain select * from user where name='1'/G

//如果你确定name字段是字符串就不要把它转化成整型,加单引号

*************************** 1. row ***************************           id: 1  select_type: SIMPLE        table: user         type: refpossible_keys: index_name_password          key: index_name_password      key_len: 111          ref: const         rows: 1        Extra: Using where1 row in set (0.00 sec)