Syntax error when creating a MySQL function

Question

I'm trying to create a function in MySQL, but getting a syntax error. This is my function:

DELIMITER $$
CREATE FUNCTION gg () 
RETURNS char(8)
DETERMINISTIC
BEGIN 
  DECLARE cod varchar(8);
  select RIGHT(MAX(idCurso),7) into cod from Curso;
  IF cod is null then
        set cod = 'C' + right('0000000' + convert(varchar(7),1),7);
    else
        set cod = 'C' + right('0000000' + convert(varchar(7), @id +1),7)
    return cod;
END$$
DELIMITER ;

I am getting this error in the set cod after the if cod is null then :

"cod" is not valid at this position, expecting an identifier

What am I doing wrong?

Answer 1

There are many issues with your function.

• + icon doesn't perform concatenation in MySQL, it is used for sum. Use CONCAT or CONCAT_WS for the same.
• Improper use of CONVERT . Please see documentation CONVERT
• Use LPAD to pad 0 to the left of your integer value and make it length to 7 .
• Removed @a , don't know from where you're accessing it, replaced it with cod value and adding 1 to it.
• Missed END IF clause.

DELIMITER $$
CREATE FUNCTION gg () RETURNS CHAR(8) DETERMINISTIC 
BEGIN 
    DECLARE cod VARCHAR(8);
    SELECT
        RIGHT(MAX(idCurso),7) INTO cod
    FROM Curso; 

    IF cod IS NULL THEN 
        SET cod = CONCAT('C', LPAD(1, 7, '0')); 
    ELSE 
        SET cod = CONCAT('C', LPAD(cod + 1, 7, '0')); 
    END IF; 
    RETURN cod; 
END$$
DELIMITER ;