---

DELIMITER $$

DROP FUNCTION IF EXISTS Dni_pr $$
CREATE FUNCTION Dni_pr(project_shifr VARCHAR(20)) 
RETURNS INT
READS SQL DATA
BEGIN
    DECLARE start_date DATE;
    
    SELECT dateStart INTO start_date 
    FROM PROJECT 
    WHERE shifr = project_shifr;
    
    IF start_date IS NULL THEN
        RETURN -1;
    END IF;
    
    -- Вызываем функцию Kol_Dney
    RETURN Kol_Dney(start_date, CURDATE());
END $$

DELIMITER ;