How to add Sequence management function to MySQL
This article introduces the relevant knowledge of "how to add Sequence management function to MySQL". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!
-- Sequence management table
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
-- A function with the current value
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
-- A function that takes the next value
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
-- functions that update the current value
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
/ *
-- testing
INSERT INTO sequence VALUES ('TestSeq', 0,1)
SELECT SETVAL ('TestSeq', 10)
SELECT CURRVAL ('TestSeq')
SELECT NEXTVAL ('TestSeq')
, /
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