Mysql with function - mysql

Question

CREATE TABLE `emp_info` (
id INT NOT NULL AUTO_INCREMENT,
user_id INT,
first_name VARCHAR(70),
last_name VARCHAR(70),
PRIMARY KEY (id),
KEY (user_id)
);
CREATE TABLE `message_info` (
id INT NOT NULL AUTO_INCREMENT,
user_id INT,
message MEDIUMTEXT,
PRIMARY KEY (id),
CONSTRAINT fk_message FOREIGN KEY(user_id) REFERENCES emp_info(user_id)
);
INSERT INTO emp_info(user_id,first_name,last_name) VALUES
(001,'Ashley','Smith'),
(002,'Valen','Hue'),
(003,'Mia','Cmd'),
(004,'Alex','Smith'),
(005,'Dy','Thomson'),
(006,'Ashley','Smith'),
(007,'Alex','Smith'),
(008,'Dy','Thomson');
INSERT INTO message_info(message) VALUES
('This is a message1 '),
('This is a message2'),
('This is not messge3'),
('This is a messagee4'),
('This is a messge5');
Hi, all I need mini help with the function.
Create a function with parameters of id user to count and return the total number of messages he/she has sent.

Answer 1

if we are talking about a specific id, the query is like:
SELECT count(*) FROM message_info where message_info.user_id = ´your_id´
To create a function is like:
DELIMETER $$
CREATE FUNCTION count_message(id INT)
RETURNS INT
DETERMINISTIC
BEGIN
DECLARE count_message INT;
select count(*) INTO count_message FROM message_info where message_info.user_id = ´your_id´;
return count_message;
END$$
DELIMITER ;
in you query insert you are missing the id user, so you need add it.