Question

I want to create the following function in Mysql, but the function does not get created but fails with an error

DELIMITER $$
CREATE FUNCTION MapAccountType(AccountTypeID INT) 
RETURNS VARCHAR(50)
DETERMINISTIC
BEGIN
    DECLARE @AccountType varchar(50);
    SELECT AccountType INTO @AccountType 
            FROM AccountType 
            WHERE AccountTypeID = AccountTypeID);
    RETURN AccountType;
END $$
DELIMITER ;

A description of my table

CREATE TABLE AccountType(
    AccountTypeID INT AUTO_INCREMENT PRIMARY KEY,
    AccountType varchar(100) UNIQUE NOT NULL
);

The error I am getting is

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 '@AccountType varchar(50);

I can’t seem to find out what I am doing wrong. Can someone please help.

Answer 1

This should work:

DELIMITER $$
CREATE FUNCTION MapAccountType(AccountTypeID INT) 
RETURNS VARCHAR(50)
DETERMINISTIC
BEGIN
    SELECT AccountType INTO @AccountType FROM AccountType
    WHERE AccountTypeID = AccountTypeID;

    RETURN @AccountType;
END $$
DELIMITER ;

This will also work:

DELIMITER $$
CREATE FUNCTION MapAccountType(AccountTypeID INT) 
RETURNS VARCHAR(50)
DETERMINISTIC
BEGIN
    DECLARE v_AccountType varchar(50) DEFAULT NULL;

    SELECT AccountType INTO v_AccountType FROM AccountType
    WHERE AccountTypeID = AccountTypeID;

    RETURN v_AccountType;
END $$
DELIMITER ;

The first example uses a “global” variable (those starting with an ‘@’ symbol). The second example uses a “local” variable.