mysql的函数使用

Posted 2023-03-24

1: SELECT CODE,NAME FROM `area` WHERE NAME='龟山市 日本'
code name
kameyama_jp 龟山市 日本'

2: SELECT CODE,MAX(NAME) FROM `area`
code name
aabenraa_dk 龟山市 日本'

请问第二个sql使用函数max时,需要怎么获取到name对应列的值kameyama_jp

SELECT CODE,NAME,其他字段
FROM `area`
order by name desc
limit 1,1;追问

这个按name降序,取一行一列数据.
和我说的使用函数,获取函数对应列的值有所不同.

追答

name降序就是取name对应最大值的行

参考技术A MAX不支持字符串类型吧。追问

这只是打一个比喻~!
寻求答案...谢谢.

MySQL函数使用

 1、mysql开启函数功能

MySQL函数不能创建的解决方法

在使用MySQL数据库时，有时会遇到mysql函数不能创建的情况。

出错信息大致类似：

ERROR 1418 (HY000): This function has none of DETERMINISTIC, NO SQL, or READS SQL DATA in its declaration and binary logging is enabled (you *might* want to use the less safe log_bin_trust_function_creators variable)
ERROR 1418 (HY000): This function has none of DETERMINISTIC, NO SQL, or READS SQL DATA in its declaration and binary logging is enabled (you *might* want to use the less safe log_bin_trust_function_creators variable)

MySQL函数不能创建，是没有开启函数功能，下面操作开启函数功能：

mysql> show variables like ‘%func%‘;
+---------------------------------+-------+
| Variable_name | Value |
+---------------------------------+-------+
| log_bin_trust_function_creators | OFF |
+---------------------------------+-------+
1 row in set (0.03 sec)

mysql> set global log_bin_trust_function_creators=1;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like ‘%func%‘;
+---------------------------------+-------+
| Variable_name | Value |
+---------------------------------+-------+
| log_bin_trust_function_creators | ON |
+---------------------------------+-------+
1 row in set (0.01 sec)

 

 2、grant 操作 MySQL 存储过程、函数权限

grant create routine on dianshang_db.* to [email protected]‘%‘;

grant alter routine on dianshang_db.* to [email protected]‘%‘;

grant execute on dianshang_db.* to [email protected]‘%‘;

 

参照文档

https://blog.csdn.net/fanhenghui/article/details/69945846