Mysql数据库（七）触发器
2024-04-18 13:21:34
一、MySQL触发器
触发器是由MySQL的基本命令事件来触发某种特定操作，这些基本的命令由INSERT、UPDATE、DELETE等事件来触发某些特定操作。满足触发器的触发条件时，数据库系统就会自动执行触发器中定义的程序语句。这样可以令某些操作之间的一致性得到协调。
1.创建MySQL触发器
mysql> CREATE TABLE IF NOT EXISTS tb_booklog(-> id int(11) PRIMARY KEY auto_increment NOT NULL,-> event varchar(200) NOT NULL,-> logtime timestamp NOT NULL DEFAULT current_timestamp-> );
Query OK, 0 rows affected (0.03 sec)mysql> DELIMITER //
mysql> CREATE TRIGGER auto_save_log BEFORE INSERT-> ON tb_bookinfo FOR EACH ROW-> INSERT INTO tb_booklog(event,logtime) values('look at me',now());-> //
Query OK, 0 rows affected (0.01 sec)
mysql> SELECT * FROM tb_bookinfo;-> //
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 |
| 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 |
| 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
3 rows in set (0.00 sec)
mysql> INSERT INTO tb_bookinfo-> (barcode,bookname,typeid,author,ISBN,price,page,bookcase,inTime,del,id)-> VALUES-> ('17120110','ShenOba',4,'ShenJiang','118',52.15,300,4,'2018-04-20',0,4);-> //
Query OK, 1 row affected (0.00 sec)mysql> SELECT * FROM tb_bookinfo;-> //
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 |
| 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 |
| 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 |
| 17120110 | ShenOba | 4 | ShenJiang | 118 | 52.15 | 300 | 4 | 2018-04-20 | 0 | 4 |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
4 rows in set (0.00 sec)mysql> SELECT * FROM tb_booklog;-> //
+----+------------+---------------------+
| id | event | logtime |
+----+------------+---------------------+
| 2 | look at me | 2018-04-18 19:40:02 |
+----+------------+---------------------+
1 row in set (0.00 sec)
2.创建具有多个执行语句的触发器
mysql> CREATE DEFINER=`root`@`localhost` TRIGGER delete_book_info BEFORE DELETE-> ON tb_bookinfo FOR EACH ROW-> BEGIN-> INSERT INTO tb_booklog(event,logtime) values('let me go',now());-> INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;-> END-> //
Query OK, 0 rows affected (0.01 sec)
血一般惨痛的教训！！！当删除表中某一条记录未能成功时，检查一下触发器什么的有没有INSERT INTO语句，如果有，检查插入值的个数和表能不能对应起来，这里的原因就是两个表不一致！！！
Microsoft Windows [版本 10.0.16299.371]
(c) 2017 Microsoft Corporation。保留所有权利。C:\Users\BigJun>mysql -uroot -p
Enter password: *********
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 23
Server version: 5.7.20 MySQL Community Server (GPL)Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> DELIMITER //
mysql> CREATE DEFINER=`root`@`localhost` TRIGGER BEFORE DELETE-> ON tb_bookinfo FOR EACH ROW-> BEGIN-> INSERT INTO tb_booklog(event,logtime) values('let me go'.now());-> INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;-> END-> //
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'BEFORE DELETE
ON tb_bookinfo FOR EACH ROW
BEGIN
INSERT INTO tb_booklog(event,log' at line 1
mysql> CREATE DEFINER=`root`@`localhost` TRIGGER delete_book_info BEFORE DELETE-> ON tb_bookinfo FOR EACH ROW-> BEGIN-> INSERT INTO tb_booklog(event,logtime) values('let me go'.now());-> INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;-> END-> //
ERROR 1046 (3D000): No database selected
mysql> use db_library;
ERROR 1049 (42000): Unknown database 'db_library;'
mysql> USE db_library;
ERROR 1049 (42000): Unknown database 'db_library;'
mysql> exit
ByeC:\Users\BigJun>mysql -uroot -p
Enter password: *********
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 24
Server version: 5.7.20 MySQL Community Server (GPL)Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| db_database13 |
| db_library |
| db_library1 |
| db_library_gbk |
| hotel |
| mybatis |
| mysql |
| mysqldb |
| performance_schema |
| se |
| spring |
| springapp |
| sys |
| test |
+--------------------+
15 rows in set (0.00 sec)mysql> use db_library;
Database changed
mysql> DELIMITER //
mysql> CREATE DEFINER=`root`@`localhost` TRIGGER delete_book_info BEFORE DELETE-> ON tb_bookinfo FOR EACH ROW-> BEGIN-> INSERT INTO tb_booklog(event,logtime) values('let me go'.now());->-> INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;-> END-> //
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '.now());INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;
' at line 4
mysql> CREATE DEFINER=`root`@`localhost` TRIGGER delete_book_info BEFORE DELETE-> ON tb_bookinfo FOR EACH ROW-> BEGIN-> INSERT INTO tb_booklog(event,logtime) values('let me go'.now());-> INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;-> END-> //
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '.now());
INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;
E' at line 4
mysql> CREATE DEFINER=`root`@`localhost` TRIGGER delete_book_info BEFORE DELETE-> ON tb_bookinfo FOR EACH ROW-> BEGIN-> INSERT INTO tb_booklog(event,logtime) values('let me go',now());-> INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;-> END-> //
Query OK, 0 rows affected (0.01 sec)mysql> select * from tb_bookinfo;-> //
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 |
| 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 |
| 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 |
| 17120110 | ShenOba | 4 | ShenJiang | 118 | 52.15 | 300 | 4 | 2018-04-20 | 0 | 4 |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
4 rows in set (0.01 sec)mysql> select * from tb_booklog;-> //
+----+------------+---------------------+
| id | event | logtime |
+----+------------+---------------------+
| 2 | look at me | 2018-04-18 19:40:02 |
+----+------------+---------------------+
1 row in set (0.00 sec)mysql> select * from tb_bookinfobak;-> //
Empty set (0.00 sec)mysql> DELETE FROM tb_bookinfo where id=4;-> //
ERROR 1136 (21S01): Column count doesn't match value count at row 1
mysql> DELETE FROM tb_bookinfo WHERE id=4;-> //
ERROR 1136 (21S01): Column count doesn't match value count at row 1
mysql> DELETE FROM tb_bookinfo WHERE id=3;-> //
ERROR 1136 (21S01): Column count doesn't match value count at row 1
mysql> DELETE FROM tb_bookinfo WHERE barcode='17120107';-> //
ERROR 1136 (21S01): Column count doesn't match value count at row 1
mysql> show triggers;-> //
+------------------+--------+-------------+--------------------------------------------------------------------------------------------------------------------------------------------------+--------+------------------------+-------------------------------------------------------------------------------------------------------------------------------------------+----------------+----------------------+----------------------+--------------------+
| Trigger | Event | Table | Statement | Timing | Created | sql_mode | Definer | character_set_client | collation_connection | Database Collation |
+------------------+--------+-------------+--------------------------------------------------------------------------------------------------------------------------------------------------+--------+------------------------+-------------------------------------------------------------------------------------------------------------------------------------------+----------------+----------------------+----------------------+--------------------+
| delete_book_info | DELETE | tb_bookinfo | BEGIN
INSERT INTO tb_booklog(event,logtime) values('let me go',now());
INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;
END | BEFORE | 2018-04-18 20:35:07.19 | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION | root@localhost | gbk | gbk_chinese_ci | utf8_general_ci |
+------------------+--------+-------------+--------------------------------------------------------------------------------------------------------------------------------------------------+--------+------------------------+-------------------------------------------------------------------------------------------------------------------------------------------+----------------+----------------------+----------------------+--------------------+
1 row in set (0.00 sec)mysql> select * from tb_bookinfo;-> //
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 |
| 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 |
| 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 |
| 17120110 | ShenOba | 4 | ShenJiang | 118 | 52.15 | 300 | 4 | 2018-04-20 | 0 | 4 |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
4 rows in set (0.00 sec)mysql> delete from tb_bookinfo where id=1;-> //
ERROR 1136 (21S01): Column count doesn't match value count at row 1
mysql> desc tb_bookinfobak;-> //
+------------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+------------------+------+-----+---------+-------+
| barcode | varchar(30) | YES | | NULL | |
| bookname | varchar(70) | YES | | NULL | |
| typeid | int(10) unsigned | YES | | NULL | |
| author | varchar(30) | YES | | NULL | |
| ISBN | varchar(20) | YES | | NULL | |
| price | float(8,2) | YES | | NULL | |
| page | int(10) unsigned | YES | | NULL | |
| bookcase | int(10) unsigned | YES | | NULL | |
| inTime | datetime(6) | YES | | NULL | |
| del | tinyint(1) | YES | | 0 | |
| id | int(11) | NO | | NULL | |
| translator | varchar(30) | NO | | NULL | |
+------------+------------------+------+-----+---------+-------+
12 rows in set (0.00 sec)mysql> alter table tb_bookinfobak drop transtor;-> //
ERROR 1091 (42000): Can't DROP 'transtor'; check that column/key exists
mysql> alter table tb_bookinfobak drop translator;-> //
Query OK, 0 rows affected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0mysql> desc tb_bookinfobak;-> //
+----------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+------------------+------+-----+---------+-------+
| barcode | varchar(30) | YES | | NULL | |
| bookname | varchar(70) | YES | | NULL | |
| typeid | int(10) unsigned | YES | | NULL | |
| author | varchar(30) | YES | | NULL | |
| ISBN | varchar(20) | YES | | NULL | |
| price | float(8,2) | YES | | NULL | |
| page | int(10) unsigned | YES | | NULL | |
| bookcase | int(10) unsigned | YES | | NULL | |
| inTime | datetime(6) | YES | | NULL | |
| del | tinyint(1) | YES | | 0 | |
| id | int(11) | NO | | NULL | |
+----------+------------------+------+-----+---------+-------+
11 rows in set (0.00 sec)mysql> desc tb_bookinfo;-> //
+----------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+------------------+------+-----+---------+-------+
| barcode | varchar(30) | YES | | NULL | |
| bookname | varchar(70) | YES | | NULL | |
| typeid | int(10) unsigned | YES | | NULL | |
| author | varchar(30) | YES | | NULL | |
| ISBN | varchar(20) | YES | | NULL | |
| price | float(8,2) | YES | | NULL | |
| page | int(10) unsigned | YES | | NULL | |
| bookcase | int(10) unsigned | YES | | NULL | |
| inTime | date | YES | | NULL | |
| del | tinyint(1) | YES | | 0 | |
| id | int(11) | NO | PRI | NULL | |
+----------+------------------+------+-----+---------+-------+
11 rows in set (0.00 sec)mysql> alter table tb_bookinfobak modify inTime date;-> //
Query OK, 0 rows affected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0mysql> desc tb_bookinfobak;-> //
+----------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+------------------+------+-----+---------+-------+
| barcode | varchar(30) | YES | | NULL | |
| bookname | varchar(70) | YES | | NULL | |
| typeid | int(10) unsigned | YES | | NULL | |
| author | varchar(30) | YES | | NULL | |
| ISBN | varchar(20) | YES | | NULL | |
| price | float(8,2) | YES | | NULL | |
| page | int(10) unsigned | YES | | NULL | |
| bookcase | int(10) unsigned | YES | | NULL | |
| inTime | date | YES | | NULL | |
| del | tinyint(1) | YES | | 0 | |
| id | int(11) | NO | | NULL | |
+----------+------------------+------+-----+---------+-------+
11 rows in set (0.00 sec)mysql> select * from tb_bookinfo;-> //
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 |
| 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 |
| 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 |
| 17120110 | ShenOba | 4 | ShenJiang | 118 | 52.15 | 300 | 4 | 2018-04-20 | 0 | 4 |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
4 rows in set (0.00 sec)mysql> select * from tb_bookbak;-> //
ERROR 1146 (42S02): Table 'db_library.tb_bookbak' doesn't exist
mysql> select * from tb_bookinfobak;-> //
Empty set (0.00 sec)mysql> select * from tb_booklog;-> //
+----+------------+---------------------+
| id | event | logtime |
+----+------------+---------------------+
| 2 | look at me | 2018-04-18 19:40:02 |
+----+------------+---------------------+
1 row in set (0.00 sec)mysql> delete from tb_bookinfo where id=1;-> //
Query OK, 1 row affected (0.01 sec)mysql> select * from tb_bookinfobak;-> //
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
1 row in set (0.00 sec)mysql> select * from tb_booklog;-> //
+----+------------+---------------------+
| id | event | logtime |
+----+------------+---------------------+
| 2 | look at me | 2018-04-18 19:40:02 |
| 8 | let me go | 2018-04-18 20:54:19 |
+----+------------+---------------------+
2 rows in set (0.00 sec)
二、查看触发器
1.SHOW TRIGGER语句
mysql> SHOW TRIGGERs\G
*************************** 1. row ***************************Trigger: delete_book_infoEvent: DELETETable: tb_bookinfoStatement: BEGIN
INSERT INTO tb_booklog(event,logtime) values('let me go',now());
INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;
ENDTiming: BEFORECreated: 2018-04-18 20:35:07.19sql_mode: ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTIONDefiner: root@localhost
character_set_client: gbk
collation_connection: gbk_chinese_ciDatabase Collation: utf8_general_ci
1 row in set (0.00 sec)
2.查看triggers表中的触发信息
（1）查看所有触发器的定义
mysql> SELECT * FROM information_schema.triggers\G
*************************** 1. row ***************************TRIGGER_CATALOG: defTRIGGER_SCHEMA: db_libraryTRIGGER_NAME: delete_book_infoEVENT_MANIPULATION: DELETEEVENT_OBJECT_CATALOG: defEVENT_OBJECT_SCHEMA: db_libraryEVENT_OBJECT_TABLE: tb_bookinfoACTION_ORDER: 1ACTION_CONDITION: NULLACTION_STATEMENT: BEGIN
INSERT INTO tb_booklog(event,logtime) values('let me go',now());
INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;
ENDACTION_ORIENTATION: ROWACTION_TIMING: BEFORE
ACTION_REFERENCE_OLD_TABLE: NULL
ACTION_REFERENCE_NEW_TABLE: NULLACTION_REFERENCE_OLD_ROW: OLDACTION_REFERENCE_NEW_ROW: NEWCREATED: 2018-04-18 20:35:07.19SQL_MODE: ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTIONDEFINER: root@localhostCHARACTER_SET_CLIENT: gbkCOLLATION_CONNECTION: gbk_chinese_ciDATABASE_COLLATION: utf8_general_ci
*************************** 2. row ***************************TRIGGER_CATALOG: defTRIGGER_SCHEMA: sysTRIGGER_NAME: sys_config_insert_set_userEVENT_MANIPULATION: INSERTEVENT_OBJECT_CATALOG: defEVENT_OBJECT_SCHEMA: sysEVENT_OBJECT_TABLE: sys_configACTION_ORDER: 1ACTION_CONDITION: NULLACTION_STATEMENT: BEGIN IF @sys.ignore_sys_config_triggers != true AND NEW.set_by IS NULL THEN SET NEW.set_by = USER(); END IF; ENDACTION_ORIENTATION: ROWACTION_TIMING: BEFORE
ACTION_REFERENCE_OLD_TABLE: NULL
ACTION_REFERENCE_NEW_TABLE: NULLACTION_REFERENCE_OLD_ROW: OLDACTION_REFERENCE_NEW_ROW: NEWCREATED: 2018-01-08 16:14:42.70SQL_MODE:DEFINER: mysql.sys@localhostCHARACTER_SET_CLIENT: utf8COLLATION_CONNECTION: utf8_general_ciDATABASE_COLLATION: utf8_general_ci
*************************** 3. row ***************************TRIGGER_CATALOG: defTRIGGER_SCHEMA: sysTRIGGER_NAME: sys_config_update_set_userEVENT_MANIPULATION: UPDATEEVENT_OBJECT_CATALOG: defEVENT_OBJECT_SCHEMA: sysEVENT_OBJECT_TABLE: sys_configACTION_ORDER: 1ACTION_CONDITION: NULLACTION_STATEMENT: BEGIN IF @sys.ignore_sys_config_triggers != true AND NEW.set_by IS NULL THEN SET NEW.set_by = USER(); END IF; ENDACTION_ORIENTATION: ROWACTION_TIMING: BEFORE
ACTION_REFERENCE_OLD_TABLE: NULL
ACTION_REFERENCE_NEW_TABLE: NULLACTION_REFERENCE_OLD_ROW: OLDACTION_REFERENCE_NEW_ROW: NEWCREATED: 2018-01-08 16:14:42.70SQL_MODE:DEFINER: mysql.sys@localhostCHARACTER_SET_CLIENT: utf8COLLATION_CONNECTION: utf8_general_ciDATABASE_COLLATION: utf8_general_ci
3 rows in set (0.03 sec)
（2）查看指定触发器名称的触发器的定义（指定数据库时将NAME改成SCHEMA，等号后面改成数据库名）
mysql> SELECT * FROM information_schema.triggers WHERE TRIGGER_NAME='delete_book_info'\G;
*************************** 1. row ***************************TRIGGER_CATALOG: defTRIGGER_SCHEMA: db_libraryTRIGGER_NAME: delete_book_infoEVENT_MANIPULATION: DELETEEVENT_OBJECT_CATALOG: defEVENT_OBJECT_SCHEMA: db_libraryEVENT_OBJECT_TABLE: tb_bookinfoACTION_ORDER: 1ACTION_CONDITION: NULLACTION_STATEMENT: BEGIN
INSERT INTO tb_booklog(event,logtime) values('let me go',now());
INSERT INTO tb_bookinfobak SELECT * FROM tb_bookinfo where id=OLD.id;
ENDACTION_ORIENTATION: ROWACTION_TIMING: BEFORE
ACTION_REFERENCE_OLD_TABLE: NULL
ACTION_REFERENCE_NEW_TABLE: NULLACTION_REFERENCE_OLD_ROW: OLDACTION_REFERENCE_NEW_ROW: NEWCREATED: 2018-04-18 20:35:07.19SQL_MODE: ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTIONDEFINER: root@localhostCHARACTER_SET_CLIENT: gbkCOLLATION_CONNECTION: gbk_chinese_ciDATABASE_COLLATION: utf8_general_ci
1 row in set (0.01 sec)
三、使用触发器
1.触发器的执行顺序
mysql> create table if not exists tb_temp(-> id int(11) PRIMARY KEY auto_increment NOT NULL,-> event varchar(200) NOT NULL,-> time timestamp NOT NULL DEFAULT current_timestamp-> );
Query OK, 0 rows affected (0.03 sec)
mysql> create table tb_bookcase(-> id int(11) PRIMARY KEY auto_increment NOT NULL,-> name varchar(200)-> );
Query OK, 0 rows affected (0.02 sec)mysql> create trigger before_in BEFORE INSERT ON-> tb_bookcase FOR EACH ROW-> INSERT INTO tb_temp(event) values('BEFORE INSERT');
Query OK, 0 rows affected (0.01 sec)mysql> create trigger after_in AFTER INSERT ON-> tb_bookcase FOR EACH ROW-> INSERT INTO tb_temp(event) values('AFTER INSERT');
Query OK, 0 rows affected (0.01 sec)mysql> select * from tb_bookcase;
Empty set (0.00 sec)mysql> select * from tb_temp;
Empty set (0.00 sec)mysql> INSERT INTO tb_bookcase(name) VALUES('左边第二个');
Query OK, 1 row affected (0.01 sec)mysql> select * from tb_bookcase;
+----+-----------------+
| id | name |
+----+-----------------+
| 1 | 左边第二个 |
+----+-----------------+
1 row in set (0.00 sec)mysql> select * from tb_temp;
+----+---------------+---------------------+
| id | event | time |
+----+---------------+---------------------+
| 1 | BEFORE INSERT | 2018-04-19 08:17:28 |
| 2 | AFTER INSERT | 2018-04-19 08:17:28 |
+----+---------------+---------------------+
2 rows in set (0.00 sec)
2.使用触发器维护冗余数据（为了避免数据不一致问题的发生，尽量不要人工维护数据，建议通过编程自动维护）
mysql> create table tb_stock(-> id int(11) PRIMARY KEY auto_increment NOT NULL.-> id int(11) PRIMARY KEY auto_increment NOT NULL.^C
mysql> create table tb_stock(-> id int(11) PRIMARY KEY auto_increment NOT NULL,-> goodsname varchar(200) NOT NULL,-> number int(11)-> );
Query OK, 0 rows affected (0.02 sec)
mysql> select * from tb_stock;
+----+-------------+--------+
| id | goodsname | number |
+----+-------------+--------+
| 1 | 小猪佩qi | 100 |
+----+-------------+--------+
1 row in set (0.00 sec)
mysql> create table tb_sell(-> id int(11) PRIMARY KEY auto_increment NOT NULL,-> goodsname varchar(200),-> number int(11)-> );-> //
Query OK, 0 rows affected (0.02 sec)mysql> select * from tb_sell;-> //
Empty set (0.00 sec)
mysql> CREATE TRIGGER auto_number AFTER INSERT-> ON tb_sell FOR EACH ROW-> BEGIN-> DECLARE sellnum int(10);-> SELECT number FROM tb_sell where id=NEW.id INTO @sellnum;-> UPDATE tb_stock SET number=number-@sellnum WHERE goodsname='小猪佩qi';-> END-> //
Query OK, 0 rows affected (0.01 sec)
mysql> INSERT INTO tb_sell(goodsname,number) VALUES-> ('小猪佩qi',2);-> //
Query OK, 1 row affected (0.01 sec)mysql> select * from tb_sell;-> //
+----+-------------+--------+
| id | goodsname | number |
+----+-------------+--------+
| 1 | 小猪佩qi | 2 |
+----+-------------+--------+
1 row in set (0.00 sec)mysql> select * from tb_stock;-> //
+----+-------------+--------+
| id | goodsname | number |
+----+-------------+--------+
| 1 | 小猪佩qi | 98 |
+----+-------------+--------+
1 row in set (0.00 sec)
四、删除触发器
转载于:https://www.cnblogs.com/BigJunOba/p/8877533.html
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