问题
Suppose I have an attribute called phone number and I would like to enforce certain validity on the entries to this field. Can I use regular expression for this purpose, since Regular Expression is very flexible at defining constraints.
回答1:
Yes, you can. MySQL supports regex (http://dev.mysql.com/doc/refman/5.6/en/regexp.html) and for data validation you should use a trigger since MySQL doesn't support CHECK constraint (you can always move to PostgreSQL as an alternative:). NB! Be aware that even though MySQL does have CHECK constraint construct, unfortunately MySQL (so far 5.6) does not validate data against check constraints. According to http://dev.mysql.com/doc/refman/5.6/en/create-table.html: "The CHECK clause is parsed but ignored by all storage engines."
You can add a check constraint for a column phone:
CREATE TABLE data (
phone varchar(100)
);
DELIMITER $$
CREATE TRIGGER trig_phone_check BEFORE INSERT ON data
FOR EACH ROW
BEGIN
IF (NEW.phone REGEXP '^(\\+?[0-9]{1,4}-)?[0-9]{3,10}$' ) = 0 THEN
SIGNAL SQLSTATE '12345'
SET MESSAGE_TEXT = 'Wroooong!!!';
END IF;
END$$
DELIMITER ;
INSERT INTO data VALUES ('+64-221221442'); -- should be OK
INSERT INTO data VALUES ('+64-22122 WRONG 1442'); -- will fail with the error: #1644 - Wroooong!!!
However you should not rely merely on MySQL (data layer in your case) for data validation. The data should be validated on all levels of your app.
来源：https://stackoverflow.com/questions/16005283/is-it-possible-to-enforce-data-checking-in-mysql-using-regular-expression