Question

我在使用数据库触发器时遇到问题，该触发器记录在表上执行的所有查询，当该查询包含4字节UTF-8字符时。

在Ubuntu 16.04上，

mysql版本是5.7.19

示例脚本：

show variables where Variable_name like 'character\_set\_%' or Variable_name like 'collation%';

drop database if exists my_test_db;
create database my_test_db;
use my_test_db;

create table my_test_table(id int not null primary key auto_increment, jdoc json not null);
create table my_test_table_log(id int not null primary key auto_increment, query varchar(1024) NOT NULL);

SELECT "insert works when trigger is not active" as "";
insert into my_test_table(jdoc) VALUES(JSON_OBJECT("Dubai was", ""));

DELIMITER |
CREATE TRIGGER log_my_test_table_queries_insert
BEFORE INSERT ON `my_test_table`
FOR EACH ROW
  BEGIN
    DECLARE original_query VARCHAR(1024);
    SET original_query = (SELECT info
                          FROM INFORMATION_SCHEMA.PROCESSLIST
                          WHERE id = CONNECTION_ID());
    INSERT INTO `my_test_table_log` (`query`) VALUES (original_query);
  END;
|
DELIMITER ;

SELECT "insert doesn't work when trigger is active" as "";
insert into my_test_table(jdoc) VALUES(JSON_OBJECT("Dubai was", ""));

我的输出：

+--------------------------+--------------------+
| Variable_name            | Value              |
+--------------------------+--------------------+
| character_set_client     | utf8mb4            |
| character_set_connection | utf8mb4            |
| character_set_database   | utf8mb4            |
| character_set_filesystem | binary             |
| character_set_results    | utf8mb4            |
| character_set_server     | utf8mb4            |
| character_set_system     | utf8               |
| collation_connection     | utf8mb4_unicode_ci |
| collation_database       | utf8mb4_unicode_ci |
| collation_server         | utf8mb4_unicode_ci |
+--------------------------+--------------------+
10 rows in set (0.00 sec)

Query OK, 2 rows affected (0.03 sec)

Query OK, 1 row affected (0.00 sec)

Database changed
Query OK, 0 rows affected (0.03 sec)

Query OK, 0 rows affected (0.02 sec)

+-----------------------------------------+
|                                         |
+-----------------------------------------+
| insert works when trigger is not active |
+-----------------------------------------+
1 row in set (0.00 sec)

Query OK, 1 row affected (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

+--------------------------------------------+
|                                            |
+--------------------------------------------+
| insert doesn't work when trigger is active |
+--------------------------------------------+
1 row in set (0.01 sec)

ERROR 1366 (HY000): Incorrect string value: '\xF0\x9F\x94\xA5")...' for column 'INFO' at row 1

数据库似乎是使用正确的字符集

创建的

SHOW CREATE TRIGGER log_my_test_table_queries_insert;
SHOW CREATE TABLE my_test_table;
SHOW CREATE TABLE my_test_table_log;

outputs

detailsdetailsdetails

Answer 1

这是因为information_schema.processlist正在使用UTF8mb3字符集。（UTF是UTFmb3的别名）。这个简单的查询说明了这一点：

mysql> select info, "" from information_schema.processlist;
+------------------------------------------------------+------+
| info                                                 | ?    |
+------------------------------------------------------+------+
| select info, "?" from information_schema.processlist |      |
+------------------------------------------------------+------+
1 row in set, 1 warning (0,00 sec)

Warning (Code 1366): Incorrect string value: '\xF0\x9F\x94\xA5" ...' for column 'INFO' at row 1

当触发器尝试将info列的内容插入另一个表时，上述警告可能会导致错误。

我认为问题是查询字符串按原样存储在processlist表中，而不将其转换为预期的字符集。我已就此提出bug report。

Answer 2

做这些

SHOW CREATE TRIGGER log_my_test_table_queries_insert;
SHOW CREATE TABLE my_test_table;
SHOW CREATE TABLE my_test_table_log;

我怀疑你会发现它们是使用错误的字符集创建的。

更改这一行可能就足够了：

create database my_test_db CHARACTER SET utf8mb4;

（我无法重现你的测试用例的问题。你使用的是什么版本的MySQL或MariaDB？）

插入触发器处于活动状态时，无法将4字节UTF-8字符/表情符号插入MySQL数据库

2 个答案: