mysql觸發(fā)器實(shí)時(shí)檢測(cè)一條語(yǔ)句進(jìn)行備份刪除思路詳解

更新時(shí)間：2021年09月19日 08:54:32 作者：我愛(ài)睡蓮

遇到過(guò)這樣一個(gè)需求，在一張表里會(huì)不時(shí)出現(xiàn) “違規(guī)” 字樣的字段，需要在出現(xiàn)這個(gè)字段的時(shí)候，把整行的數(shù)據(jù)刪掉，針對(duì)這個(gè)需求我們?cè)撊绾尾僮髂兀旅娓S小編看下mysql觸發(fā)器實(shí)時(shí)檢測(cè)一條語(yǔ)句進(jìn)行備份刪除的解決思路，一起看看吧

問(wèn)題描述：用戶(hù)有一個(gè)這樣一個(gè)需求，在一張表里會(huì)不時(shí)出現(xiàn) “違規(guī)” 字樣的字段，需要在出現(xiàn)這個(gè)字段的時(shí)候，把整行的數(shù)據(jù)刪掉。這是個(gè)采集任務(wù)，如果發(fā)現(xiàn)有“違規(guī)”字樣的數(shù)據(jù)，會(huì)整點(diǎn)或者什么時(shí)間進(jìn)行統(tǒng)一上報(bào)，也無(wú)法對(duì)源頭進(jìn)行控制讓這種數(shù)據(jù)不生成。

現(xiàn)在需要實(shí)現(xiàn)以下需求：

1.實(shí)時(shí)檢測(cè)這條數(shù)據(jù)的產(chǎn)生，發(fā)現(xiàn)后刪除

2.在刪除之前作備份這條數(shù)據(jù)

解決思路：

需要明確解決思路，

1.首先是如何實(shí)時(shí)探測(cè)刪除？詢(xún)問(wèn)開(kāi)發(fā)，這條數(shù)據(jù)的生成方式為insert，就可以做一個(gè)當(dāng)表做插入的時(shí)候，然后做一個(gè)after insert 做delete數(shù)據(jù)的觸發(fā)器

2.如何進(jìn)行備份？何種方式備份？能不能備份到一個(gè)表里，這個(gè)表里記錄每次插入的時(shí)間，建立這個(gè)備份表可以取與原表結(jié)構(gòu)基本相同，但是備份表要?jiǎng)h除原表的自增屬性，主鍵，外鍵等屬性，新增一個(gè)時(shí)間戳字段，方便記錄每次備份數(shù)據(jù)的時(shí)間，刪除以上屬性是為了能夠把數(shù)據(jù)寫(xiě)入備份表中

3.如何在刪除之前做備份呢？一開(kāi)始想的是放到一個(gè)觸發(fā)器就行，先把數(shù)據(jù)進(jìn)行備份，然后后面跟著一條刪除，測(cè)試的時(shí)候行不通

測(cè)試方案：

先準(zhǔn)備一些測(cè)試數(shù)據(jù)和測(cè)試表

1.建立測(cè)試數(shù)據(jù)

mysql> show create table student;
+---------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table   | Create Table                                                                                                                                                                                                                                                             |
+---------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| student | CREATE TABLE `student` (
  `Sno` char(9) NOT NULL,
  `Sname` char(20) NOT NULL,
  `Ssex` char(2) DEFAULT NULL,
  `Sage` smallint DEFAULT NULL,
  `Sdept` char(20) DEFAULT NULL,
  PRIMARY KEY (`Sno`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |
+---------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

2.建立備份表。查看建表語(yǔ)句，正式環(huán)境是不知道原表的表結(jié)構(gòu)的，需要有改原表結(jié)構(gòu)，并創(chuàng)建新備份表的操作的

原表建表語(yǔ)句

mysql> show create table student;
+---------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table   | Create Table                                                                                                                                                                                                                                                             |
+---------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| student | CREATE TABLE `student` (
  `Sno` char(9) NOT NULL,
  `Sname` char(20) NOT NULL,
  `Ssex` char(2) DEFAULT NULL,
  `Sage` smallint DEFAULT NULL,
  `Sdept` char(20) DEFAULT NULL,
  PRIMARY KEY (`Sno`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |
+---------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

3.準(zhǔn)備備份語(yǔ)句，刪除語(yǔ)句，插入測(cè)試語(yǔ)句

備份語(yǔ)句（因?yàn)閭浞荼矶嘁粋€(gè)時(shí)間戳的字段，所以備份語(yǔ)句要做修改一下）

mysql> show create table student_bak;
+-------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| student_bak | CREATE TABLE `student_bak` (
`Sno` char(9) NOT NULL,
`Sname` char(20) NOT NULL,
`Ssex` char(2) DEFAULT NULL,
`Sage` smallint DEFAULT NULL,
`Sdept` char(20) DEFAULT NULL,
`create_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |
+-------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

備份效果

插入測(cè)試語(yǔ)句：

insert into student values('201215124','張三','男',20,'EL');

刪除語(yǔ)句（刪除數(shù)據(jù)一定要寫(xiě)精準(zhǔn)了，到時(shí)候刪什么，就要備份什么）

delete from student where Sdept='EL';

4.實(shí)際測(cè)試方案

4.1 把兩條語(yǔ)句寫(xiě)進(jìn)一個(gè)觸發(fā)器(操作失敗，邏輯執(zhí)行不成功)

drop trigger if exists test_trigger;
DELIMITER $
CREATE TRIGGER test_trigger
AFTER
INSERT ON student2
FOR EACH ROW
BEGIN
insert into student_bak(Sno,Sname,Ssex,Sage,Sdept) select * from student where Sdept='EL';
delete from student where Sdept='EL';
END $
DELIMITER ;

4.2 準(zhǔn)備兩個(gè)單獨(dú)的觸發(fā)器，一個(gè)是當(dāng)原表出現(xiàn)這條數(shù)據(jù)時(shí)，插入到備份表實(shí)現(xiàn)備份的效果。第二個(gè)觸發(fā)器是做備份表備份完數(shù)據(jù)之后，在做一個(gè)刪除原表該條數(shù)據(jù)的觸發(fā)器，然后實(shí)現(xiàn)備份完刪除的效果（還是操作失?。瑘?zhí)行報(bào)錯(cuò)，說(shuō)的是觸發(fā)器有沖突還是什么的，這樣做讓數(shù)據(jù)庫(kù)不知道執(zhí)行邏輯了。

4.3 做一個(gè)在原表如果進(jìn)行刪除目標(biāo)數(shù)據(jù)，然后備份該條數(shù)據(jù)到備份表的觸發(fā)器。最后再實(shí)現(xiàn)實(shí)時(shí)探測(cè)目標(biāo)數(shù)據(jù)出現(xiàn)然后刪除的操作就行了，不局限于觸發(fā)器的思維，做一個(gè)定時(shí)任務(wù)就可以了（操作成功）

比如下面測(cè)試的當(dāng)數(shù)據(jù)庫(kù)的表中Sdept字段出現(xiàn)了一個(gè)叫‘EL'的字段時(shí)，需要把整行數(shù)據(jù)刪除掉

drop trigger if exists student_bak_trigger;
DELIMITER $
CREATE TRIGGER student_bak_trigger 
BEFORE 
DELETE ON student 
FOR EACH ROW 
BEGIN   
insert into  student_bak(Sno,Sname,Ssex,Sage,Sdept) select * from student where Sdept='EL';
END $
DELIMITER ;

這個(gè)觸發(fā)器就實(shí)現(xiàn)了，如果原表的目標(biāo)數(shù)據(jù)被刪除了，觸發(fā)器觸發(fā)了就會(huì)備份該條數(shù)據(jù)

mysql> select * from student;
+-----------+--------+------+------+-------+
| Sno       | Sname  | Ssex | Sage | Sdept |
+-----------+--------+------+------+-------+
| 201215121 | 李勇   | 男   |   20 | CS    |
| 201215122 | 劉晨   | 女   |   19 | CS    |
| 201215123 | 王敏   | 女   |   18 | MA    |
| 201215130 | 兵丁   | 男   |   20 | CH    |
+-----------+--------+------+------+-------+
4 rows in set (0.00 sec)

mysql> select * from student_bak;
+-----------+--------+------+------+-------+---------------------+
| Sno       | Sname  | Ssex | Sage | Sdept | create_date         |
+-----------+--------+------+------+-------+---------------------+
| 201215124 | 張三   | 男   |   20 | EL    | 2021-09-18 15:42:20 |
+-----------+--------+------+------+-------+---------------------+
1 row in set (0.00 sec)

mysql> insert into student values('201215125','王五','男',30,'EL');
Query OK, 1 row affected (0.00 sec)

mysql> select * from student;
+-----------+--------+------+------+-------+
| Sno       | Sname  | Ssex | Sage | Sdept |
+-----------+--------+------+------+-------+
| 201215121 | 李勇   | 男   |   20 | CS    |
| 201215122 | 劉晨   | 女   |   19 | CS    |
| 201215123 | 王敏   | 女   |   18 | MA    |
| 201215125 | 王五   | 男   |   30 | EL    |
| 201215130 | 兵丁   | 男   |   20 | CH    |
+-----------+--------+------+------+-------+
5 rows in set (0.00 sec)

mysql> select * from student_bak;
+-----------+--------+------+------+-------+---------------------+
| Sno       | Sname  | Ssex | Sage | Sdept | create_date         |
+-----------+--------+------+------+-------+---------------------+
| 201215124 | 張三   | 男   |   20 | EL    | 2021-09-18 15:42:20 |
+-----------+--------+------+------+-------+---------------------+
1 row in set (0.00 sec)

mysql> delete from student where Sdept='EL';
Query OK, 1 row affected (0.01 sec)

mysql> select * from student_bak;
+-----------+--------+------+------+-------+---------------------+
| Sno       | Sname  | Ssex | Sage | Sdept | create_date         |
+-----------+--------+------+------+-------+---------------------+
| 201215124 | 張三   | 男   |   20 | EL    | 2021-09-18 15:42:20 |
| 201215125 | 王五   | 男   |   30 | EL    | 2021-09-18 15:47:28 |
+-----------+--------+------+------+-------+---------------------+
2 rows in set (0.00 sec)

最后實(shí)現(xiàn)一個(gè)定時(shí)任務(wù)，來(lái)循環(huán)的刪除一個(gè)叫‘EL'的字段的整行數(shù)據(jù)，這里的定時(shí)任務(wù)是面向全局的，一定要加上數(shù)據(jù)庫(kù)名和具體表名，定時(shí)任務(wù)的執(zhí)行速度是可以手動(dòng)調(diào)整的，下面為3s/次,以便實(shí)現(xiàn)需要的效果

create event if not exists e_test_event
on schedule every 3 second 
on completion preserve
do delete from abc.student where Sdept='EL';

關(guān)閉定時(shí)任務(wù)：

mysql> alter event e_test_event ON COMPLETION PRESERVE DISABLE;
Query OK, 0 rows affected (0.00 sec)

查看定時(shí)任務(wù)：

mysql> select * from information_schema.events\G;*************************** 4. row ***************************
       EVENT_CATALOG: def
        EVENT_SCHEMA: abc
          EVENT_NAME: e_test_event
             DEFINER: root@%
           TIME_ZONE: SYSTEM
          EVENT_BODY: SQL
    EVENT_DEFINITION: delete from abc.student where Sdept='EL'
          EVENT_TYPE: RECURRING
          EXECUTE_AT: NULL
      INTERVAL_VALUE: 3
      INTERVAL_FIELD: SECOND
            SQL_MODE: ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION
              STARTS: 2021-09-17 13:35:44
                ENDS: NULL
              STATUS: ENABLED
       ON_COMPLETION: PRESERVE
             CREATED: 2021-09-17 13:35:44
        LAST_ALTERED: 2021-09-17 13:35:44
       LAST_EXECUTED: 2021-09-18 15:43:35
       EVENT_COMMENT: 
          ORIGINATOR: 3330614
CHARACTER_SET_CLIENT: utf8mb4
COLLATION_CONNECTION: utf8mb4_0900_ai_ci
  DATABASE_COLLATION: utf8mb4_0900_ai_ci
4 rows in set (0.00 sec)

查看觸發(fā)器：

mysql> select * from information_schema.triggers\G;
*************************** 5. row ***************************
           TRIGGER_CATALOG: def
            TRIGGER_SCHEMA: abc
              TRIGGER_NAME: student_bak_trigger
        EVENT_MANIPULATION: DELETE
      EVENT_OBJECT_CATALOG: def
       EVENT_OBJECT_SCHEMA: abc
        EVENT_OBJECT_TABLE: student
              ACTION_ORDER: 1
          ACTION_CONDITION: NULL
          ACTION_STATEMENT: BEGIN   
insert into  student_bak(Sno,Sname,Ssex,Sage,Sdept) select * from student where Sdept='EL';
END
        ACTION_ORIENTATION: ROW
             ACTION_TIMING: BEFORE
ACTION_REFERENCE_OLD_TABLE: NULL
ACTION_REFERENCE_NEW_TABLE: NULL
  ACTION_REFERENCE_OLD_ROW: OLD
  ACTION_REFERENCE_NEW_ROW: NEW
                   CREATED: 2021-09-18 15:41:48.53
                  SQL_MODE: ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION
                   DEFINER: root@%
      CHARACTER_SET_CLIENT: utf8mb4
      COLLATION_CONNECTION: utf8mb4_0900_ai_ci
        DATABASE_COLLATION: utf8mb4_0900_ai_ci
5 rows in set (0.00 sec)

實(shí)現(xiàn)效果：

到此這篇關(guān)于mysql觸發(fā)器實(shí)時(shí)檢測(cè)一條語(yǔ)句進(jìn)行備份刪除思路詳解的文章就介紹到這了,更多相關(guān)mysql觸發(fā)器備份刪除內(nèi)容請(qǐng)搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家！

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