mysql 增加sequence

-- Sequence 管理表

DROP TABLE IF EXISTS sequence;

CREATE TABLE sequence (

name VARCHAR(50) NOT NULL,

current_value INT NOT NULL,

increment INT NOT NULL DEFAULT 1,

PRIMARY KEY (name)

) ENGINE=InnoDB;

-- 取当前值的函数

DROP FUNCTION IF EXISTS currval;

DELIMITER $

CREATE FUNCTION currval (seq_name VARCHAR(50))

RETURNS INTEGER

LANGUAGE SQL

DETERMINISTIC

CONTAINS SQL

SQL SECURITY DEFINER

COMMENT ''

BEGIN

DECLARE value INTEGER;

SET value = 0;

SELECT current_value INTO value

FROM sequence

WHERE name = seq_name;

RETURN value;

END

$

DELIMITER ;

-- 取下一个值的函数

DROP FUNCTION IF EXISTS nextval;

DELIMITER $

CREATE FUNCTION nextval (seq_name VARCHAR(50))

RETURNS INTEGER

LANGUAGE SQL

DETERMINISTIC

CONTAINS SQL

SQL SECURITY DEFINER

COMMENT ''

BEGIN

UPDATE sequence

SET current_value = current_value + increment

WHERE name = seq_name;

RETURN currval(seq_name);

END

$

DELIMITER ;

-- 更新当前值的函数

DROP FUNCTION IF EXISTS setval;

DELIMITER $

CREATE FUNCTION setval (seq_name VARCHAR(50), value INTEGER)

RETURNS INTEGER

LANGUAGE SQL

DETERMINISTIC

CONTAINS SQL

SQL SECURITY DEFINER

COMMENT ''

BEGIN

UPDATE sequence

SET current_value = value

WHERE name = seq_name;

RETURN currval(seq_name);

END

$

DELIMITER ;

/*

-- 测试

INSERT INTO sequence VALUES ('TestSeq', 0, 1);

SELECT SETVAL('TestSeq', 10);

SELECT CURRVAL('TestSeq');

SELECT NEXTVAL('TestSeq');

*/