I would like to auto_increment two different tables in a single mysql database, the first by multiples of 1 and the other by 5 is this possible using the auto_increment feature as I seem to only be able to set auto_increment_increment globally.
If auto_increment_increment is not an option what is the best way to replicate this
Syntax. In MySQL, the syntax to change the starting value for an AUTO_INCREMENT column using the ALTER TABLE statement is: ALTER TABLE table_name AUTO_INCREMENT = start_value; table_name.
To get the next auto increment id in MySQL, we can use the function last_insert_id() from MySQL or auto_increment with SELECT. Creating a table, with “id” as auto-increment. Inserting records into the table. To display all the records.
Here's the syntax of ALTER TABLE statement, ALTER TABLE table_name MODIFY column_name INT NOT NULL AUTO_INCREMENT PRIMARY KEY; In the above statement, you need to specify the table_name and column_name. Here's the SQL statement to add AUTO INCREMENT constraint to id column.
No. A primary key must be unique and that has to be 100% guaranteed, and NON NULL A primary key should be stable if ever possible and not change.
Updated version: only a single id
field is used. This is very probably not atomic, so use inside a transaction if you need concurrency:
http://sqlfiddle.com/#!2/a4ed8/1
CREATE TABLE IF NOT EXISTS person (
id INT NOT NULL AUTO_INCREMENT,
PRIMARY KEY ( id )
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1;
CREATE TRIGGER insert_kangaroo_id BEFORE INSERT ON person FOR EACH ROW BEGIN
DECLARE newid INT;
SET newid = (SELECT AUTO_INCREMENT
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = DATABASE()
AND TABLE_NAME = 'person'
);
IF NEW.id AND NEW.id >= newid THEN
SET newid = NEW.id;
END IF;
SET NEW.id = 5 * CEILING( newid / 5 );
END;
Old, non working "solution" (the before insert trigger can't see the current auto increment value):
http://sqlfiddle.com/#!2/f4f9a/1
CREATE TABLE IF NOT EXISTS person (
secretid INT NOT NULL AUTO_INCREMENT,
id INT NOT NULL,
PRIMARY KEY ( secretid )
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1;
CREATE TRIGGER update_kangaroo_id BEFORE UPDATE ON person FOR EACH ROW BEGIN
SET NEW.id = NEW.secretid * 5;
END;
CREATE TRIGGER insert_kangaroo_id BEFORE INSERT ON person FOR EACH ROW BEGIN
SET NEW.id = NEW.secretid * 5; -- NEW.secretid is empty = unusuable!
END;
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With