MySQL Set Variables in While-Loop with If-Condition

I am working on a procedure which is doing the following: With a cursor declared I want to go through all entries of a table to find entries where the given period is covering the one from the cursor.

Example: a student A went to school at grade x from date 3 to date 6. Let's find all who studied with him at least one time for the same class.

The while-loop would be applied to the same table. But I want to just find out if there is at least one entry or not. So the while loop should stop if the first entry appears.

Example: A student B could have visited the same class as A did. But for a year he has been in another class. Just for example.

And here is my problem. I have two variables to set and I get a syntax error.

DELIMITER $$
DROP PROCEDURE IF EXISTS coworkers$$

CREATE PROCEDURE coworkers(
IN gus INT, 
IN rus INT,
OUT gto INT 

)
BEGIN
    DECLARE recCID INT;
    DECLARE recSDT DATE;
    DECLARE recEDT DATE;
    DECLARE done INT DEFAULT FALSE;

    DECLARE ctr INT;



    DECLARE cwrk CURSOR FOR
        SELECT comp_id, start_date, end_date FROM skill_cv_test WHERE usr_id = rus;
    DECLARE CONTINUE HANDLER 
        FOR NOT FOUND
        SET done = TRUE;

    OPEN cwrk;
    SET ctr = 0;
    loop_cwrk: WHILE(ctr<1) DO 

        FETCH cwrk INTO recCID, recSDT, recEDT;

        IF EXISTS
        (SELECT *
        FROM skill_cv_test AS m
        WHERE m.usr_Id = gus AND m.usr_id != rus AND (m.start_date < recSDT OR m.end_date <= recEDT) AND m.comp_id = recCID)
        THEN
        SET ctr = 1,
        SET gto = 1;


        IF done THEN
            LEAVE loop_cwrk;
        END IF;



    END WHILE loop_cwrk;
    CLOSE cwrk;

end $$
delimiter ;
CALL coworkers(2,1,@gto);  

I have tried different formats for the section THEN SET... which is the problem. Here is the error code:

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 ''ctr' := 1, SET 'gto' ;= 1;

Here you can see what else I have tried (among others). Probably it's a totally wrong approach.

Btw: the Select within the loop is only a placeholder to get the whole procedure work.

But now, what am I doing wrong?

Thanks in advance.

SOLUTION

DELIMITER $$
DROP PROCEDURE IF EXISTS coworkers$$

CREATE PROCEDURE coworkers(
IN gus INT, 
IN rus INT,
OUT gto INT 

)
BEGIN
    DECLARE recCID INT;
    DECLARE recSDT DATE;
    DECLARE recEDT DATE;
    DECLARE done INT DEFAULT FALSE;

    DECLARE ctr INT;



    DECLARE cwrk CURSOR FOR
        SELECT comp_id, start_date, end_date FROM skill_cv_test WHERE usr_id = rus;
    DECLARE CONTINUE HANDLER 
        FOR NOT FOUND
        SET done = TRUE;

    OPEN cwrk;
    SET ctr = 0;
    loop_cwrk: WHILE(ctr<1) DO 

        FETCH cwrk INTO recCID, recSDT, recEDT;

        IF EXISTS
           (SELECT *
            FROM skill_cv_test AS m
              WHERE m.usr_Id = gus AND m.usr_id != rus AND (m.start_date < recSDT 
             OR m.end_date <= recEDT) AND m.comp_id = recCID)
          THEN
            SET ctr = 1;
            SET gto = 1;
        END IF;


        IF done THEN
            LEAVE loop_cwrk;
        END IF;



    END WHILE loop_cwrk;
    CLOSE cwrk;

end $$
delimiter ;
CALL coworkers(2,1,@gto);