How to force a varchar number into a string?

[Zubi Mondragon]

Hello,

I'm doing a program in which you can reset a users password. This password needs to contain enlist one number in order to be "TRUE" among others (which are already done).

I have been looking for information about how to accomplish this task but my efforts haven't get me a solution.

I have found things about "rtrim" (which I think have nothing to do with what I'm trying), REGEXP_LIKE (could it be that the "like" is only for Oracle?).

Before I post the function know that this one serves no purpose but my own learning. Basically, I'm quite new at this.

Here goes the function:

delimiter //

drop function if exists login;

Create Function login (nombreusuario varchar(20), password varchar (10), repite varchar (10), vieja varchar (10))

Returns boolean no SQL

begin
/* Comparar los valores nombre y password con los reales */
declare comparacion varchar(30);
declare compa varchar(30);
set comparacion = (SELECT nombre
FROM usuarios
WHERE (nombre = nombreusuario)) ;
set compa = (SELECT contrasena
FROM usuarios
WHERE (nombre = nombreusuario));

if (comparacion = nombreusuario) and (compa = vieja) and length(password)>=6 and (password = repite) then

/* Hacer el UPDATE */
UPDATE usuarios
SET contrasena = password
WHERE nombre = nombreusuario;
/*Como es verdadero devuelve verdadero */
Return TRUE;
else
Return FALSE ;
end if;
end
//

delimiter ;

...........

I have try the next modification on the "if" line:

if (comparacion = nombreusuario) and (compa = vieja) and length(password)>=6 and REGEXP_LIKE (password, '[0-9]') and (password = repite) then

But it comes up with this error when I try to use the function:

ERROR 1305 (42000): FUNCTION incidencias.REGEXP_LIKE does not exist

What should I add into the if line to force a number on the password?

Thank you very much for your time.