mysql提示:Illegal mix of collations for operation ‘UNION’

作者:袖梨 2022-11-14


语句很简单

代码如下 复制代码

$connection=mysql_connect("localhost","root","password"); //连接并选择数据库服务器
mysql_select_db("test",$connection);
$query="select * from users where name='你好'";
$result=mysql_query($query,$connection);
while($row=mysql_fetch_array($result))
{
echo "用户ID:".$row[0]."
"; //也可以写做$row["user_id"]
echo "用户名:".$row[1]."
"; //也可以写做$row["user_name"]
}
?>

运行结果提示

Error: Illegal mix of collations (gbk_chinese_ci,IMPLICIT) and (latin1_swedish_ci,COERCIBLE) for operation '='

意思是说:操作符“=”比较的字符集不一致,一个是gbk_chinese_ci,一个是latin1_swedish_ci。

首先、查看mysql的my.cnf,确认为utf8

代码如下 复制代码


mysql> show variables like "%char%";

+--------------------------+-------------------------------------+

| Variable_name | Value |

+--------------------------+-------------------------------------+

| character_set_client | utf8 |

| character_set_connection | utf8 |

| character_set_database | latin1 |

| character_set_filesystem | binary |

| character_set_results | utf8 |

| character_set_server | utf8 |

| character_set_system | utf8 |

| character_sets_dir | D:/MySQL Server 5.0/share/charsets/ |

+--------------------------+-------------------------------------+

8 rows in set (0.00 sec)


mysql> show variables like "%coll%";

+----------------------+-------------------+

| Variable_name | Value |

+----------------------+-------------------+

| collation_connection | utf8_general_ci |

| collation_database | latin1_swedish_ci |

| collation_server | utf8_general_ci |

+----------------------+-------------------+

3 rows in set (0.00 sec)

然后将数据库中所有编码方式改为统一:

代码如下 复制代码


mysql> set character_set_database=utf8;

Query OK, 0 rows affected (0.00 sec)

mysql> set collation_database= utf8_general_ci

重新查看字符集及数据表字段编码字符是否一致:


总结

utf8_bin
utf8_general_ci
utf8_unicode_ci

utf8_bin 与 utf8_general_ci 可以

utf8_bin 与 utf8_unicode_ci 可以

utf8_general_ci 与 utf8_unicode_ci 不可以

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