mysql stored function return total - mysql

Question

I have a mysql table of employees with columns surname and workhours for each employee . I am trying to create a stored function that takes a letter as input and returns the sum of workhours of all employees whose surname starts from the input letter .This is basically an easy task but I am a complete beginner in sql and I need your help .
What I tried :
CREATE FUNCTION sumOfTotalSickHours(letter CHAR(1))
RETURNS DOUBLE DETERMINISTIC
BEGIN
DECLARE total DOUBLE DEFAULT 0
SELECT SUM(sickleavehours) INTO total
FROM employee where lastName LIKE '#letter%'
RETURN total
END
With my above code I get a syntax error since I do not know how to write the query correctly .

Answer 1

First of all, each statement needs to end with a semicolon (;).
Be sure you read https://dev.mysql.com/doc/refman/8.0/en/stored-programs-defining.html to understand how to use DELIMITER when defining stored programs.
Also to reference an input variable, don't put inside quotes.
And don't use #letter because variables with the # sigil are not the same variable as without the sigil.
So for example:
CREATE FUNCTION sumOfTotalSickHours(letter CHAR(1))
RETURNS DOUBLE DETERMINISTIC
BEGIN
DECLARE total DOUBLE DEFAULT 0;
SELECT SUM(sickleavehours) INTO total
FROM employee where lastName LIKE CONCAT(letter, '%');
RETURN total;
END