mysql實現nextVal功能,即便用代理表實現其餘表的主鍵自增加

首先建立表：CREATE TABLE sys_sequence (
NAME varchar(50) NOT NULL,
CURRENT_VALUE int(11) NOT NULL DEFAULT '0',
INCREMENT int(11) NOT NULL DEFAULT '1',
PRIMARY KEY (NAME)
)
插入記錄：INSERT INTO SYS_SEQUENCE(NAME,CURRENT_VALUE,INCREMENT) VALUES('TBL_FS', 1,1)
執行函數：DELIMITER $$

DROP FUNCTION IF EXISTS currval$$

CREATE DEFINER=root@% FUNCTION currval(seq_name VARCHAR(50)) RETURNS INT(11)
BEGIN
DECLARE VALUE INTEGER;
SET VALUE=0;
SELECT current_value INTO VALUE
FROM sys_sequence
WHERE NAME=seq_name;
RETURN VALUE;
END$$

DELIMITER ;
查詢記錄：select currval('TBL_FS');
若是出現Error Code: 1449 The user specified as a definer ('root'@'%') does not exist 錯誤，則執行以下sql：grant all privileges on . to root@"%" identified by "password";
flush privileges;

繼續執行當前記錄sql則成功
建立nextval函數 ：
DELIMITER $$
DROP FUNCTION IF EXISTS nextval$$

CREATE DEFINER=root@% FUNCTION nextval(seq_name varchar(50)) RETURNS int(11)
BEGIN
UPDATE sys_sequence
SET CURRENT_VALUE = CURRENT_VALUE + INCREMENT
where name=seq_name;
return currval(seq_name);
END$$
建立好了表以後 ：如圖

NAME字段爲代理表名稱，原來爲 TBL_FS，此處我修改了，current_value爲當前序號，INCREMENT爲步長。

接下來在mybatis配置文件目錄下建立mapper文件：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="MySQLFunctionMapper">

<select id="getNexVal" parameterType="string" resultType="int">
    select nextval(#{table_name})
</select>

<select id="getCurrVal" parameterType="string" resultType="int">
    select currval(#{table_name})
</select>

</mapper>

接下來在service層寫對應的獲取數據方法：
@Service
public class MySQLFunctionServiceImpl implements MySQLFunctionService{

@Resource(name = "daoSupport")
private DaoSupport dao;    //DaoSupport封裝了對應mybatis操做數據庫的方法，上篇文章有介紹

@Override
public int getNexVal(String table_name) {
    // TODO Auto-generated method stub
    return (int) dao.findForObject("MySQLFunctionMapper.getNexVal", table_name);
}

@Override
public int getCurrVal(String table_name) {
    // TODO Auto-generated method stub
    return (int) dao.findForObject("MySQLFunctionMapper.getCurrVal", table_name);
}

}

這樣就能夠調用getNexVal方法獲取代理表中的ID值，再對應賦值到其餘表的主鍵中，通常可在controller調用給其餘表的主鍵賦值後存入數據庫