sql - MySQL add column if not exist

IF NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.COLUMNS
  WHERE TABLE_NAME = 'email_subscription' AND COLUMN_NAME = 'subscribe_all')
  THEN 

  ALTER TABLE email_subscription
  ADD COLUMN subscribe_all TINYINT(1) DEFAULT 1,
  ADD COLUMN subscribe_category varchar(512) DEFAULT NULL;

I had a look at huge amount of examples. but this query doesn't work, I got error of:

ERROR 1064 (42000): You have an error in your SQL syntax; check the
manual that corresponds to your MySQL server version for the right

syntax to use near 'IF NOT EXISTS (SELECT * FROM
INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME =' at line 1

Answer

you can create a procedure for the query,

DELIMITER $$
CREATE PROCEDURE Alter_Table()
BEGIN
    DECLARE _count INT;

    SET _count = (  SELECT COUNT(*) 
                    FROM INFORMATION_SCHEMA.COLUMNS
                    WHERE   TABLE_NAME = 'email_subscription' AND 
                            COLUMN_NAME = 'subscribe_all');
    IF _count = 0 THEN
        ALTER TABLE email_subscription
            ADD COLUMN subscribe_all TINYINT(1) DEFAULT 1,
            ADD COLUMN subscribe_category varchar(512) DEFAULT NULL;
    END IF;
END $$

DELIMITER ;