How to create two auto increment column in mysql?

Question

CREATE TRIGGER test1 AFTER INSERT ON `course_metadata_31`
 FOR EACH ROW BEGIN
 update `course_metadata_31`set `articleID`=`articleID`+1
 END;

I am

Answer 1

No idea why you need two columns auto incrementing values, there is no point... but if you insist -
You can accomplish it in a UDF or SP this way you have multiple columns auto incrementing a value.

EXAMPLE #1: STORED PROCEDURE (SP)


Table

CREATE TABLE tests (
    test_id INT(10) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    test_num INT(10) NULL,
    test_name VARCHAR(10) NOT NULL
);

Stored Procedure

DELIMITER $$
CREATE PROCEDURE autoInc (name VARCHAR(10))
    BEGIN
        DECLARE getCount INT(10);

        SET getCount = (
            SELECT COUNT(test_num)
            FROM tests) + 1;

        INSERT INTO tests (test_num, test_name)
            VALUES (getCount, name);
    END$$
DELIMITER ;

Call the SP

CALL autoInc('one');
CALL autoInc('two');
CALL autoInc('three');

Look up the table

SELECT * FROM tests;

+---------+----------+-----------+
| test_id | test_num | test_name |
+---------+----------+-----------+
|       1 |       1  | one       |
|       2 |       2  | two       |
|       3 |       3  | three     |
+---------+----------+-----------+

---

EXAMPLE #2: USER-DEFINED FUNCTION (UDF)


Table

CREATE TABLE tests (
    test_id INT(10) NOT NULL PRIMARY KEY AUTO_INCREMENT,
    test_num INT(10) NULL,
    test_name VARCHAR(10) NOT NULL
);

User-defined Function

DELIMITER $$
CREATE FUNCTION autoInc ()
    RETURNS INT(10)
    BEGIN
        DECLARE getCount INT(10);

        SET getCount = (
            SELECT COUNT(test_num)
            FROM tests) + 1;

        RETURN getCount;
    END$$
DELIMITER ;

Insert using the UDF

INSERT INTO tests (test_num, test_name) VALUES (autoInc(), 'one');
INSERT INTO tests (test_num, test_name) VALUES (autoInc(), 'two');
INSERT INTO tests (test_num, test_name) VALUES (autoInc(), 'three');

Look up the table

SELECT * FROM tests;

+---------+----------+-----------+
| test_id | test_num | test_name |
+---------+----------+-----------+
|       1 |       1  | one       |
|       2 |       2  | two       |
|       3 |       3  | three     |
+---------+----------+-----------+

These have been tested and verified. I'd personally use the function, it's more flexible.