MySQL 8.0

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CREATE TABLE projects
    (`ID` int, `ProjID` int, `ActiveFrom` varchar(10), `ActiveTo` varchar(10))
;
    

INSERT INTO projects
    (`ID`, `ProjID`, `ActiveFrom`, `ActiveTo`)
VALUES
    (1, 20, '2018-01-01', '2018-01-20'),
    (2, 20, '2018-02-05', '2018-02-12'),
    (3, 20, '2018-02-20', '2018-02-27'),
    (4, 30, '2018-01-15', '2018-02-15')
;
CREATE FUNCTION check_activity(project_id INT, check_date DATE)
RETURNS BOOLEAN
DETERMINISTIC
BEGIN
  RETURN (SELECT MAX(check_date BETWEEN ActiveFrom AND ActiveTo) FROM projects WHERE ProjId = project_id);
END
SELECT check_activity(20, '2018-01-10'), check_activity(20, '2018-02-01')


check_activity(20, '2018-01-10')
check_activity(20, '2018-02-01')


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