sql根據小時判斷是早晨仍是下午等

        SELECT
        ec.title,
        CONCAT(ec.cdate,' ',ec.ctime) AS `start`,
        CONCAT(ec.edate,' ',ec.etime) AS `end`,
        CASE
       WHEN HOUR(ec.ctime) BETWEEN 9 AND 12 THEN 0
       WHEN HOUR(ec.ctime) BETWEEN 12 AND 15 THEN 1
       WHEN HOUR(ec.ctime) BETWEEN 15 AND 18 THEN 2
       WHEN HOUR(ec.ctime) BETWEEN 18 AND 21 THEN 3
    ELSE 4 END timeType,
        ec.content,
        ec.teacherID,
        e.couserType,
        e.instituId
        FROM
        `eud_courescatalog` ec LEFT JOIN edu_course e ON ec.cid=e.tid
        WHERE
        e.couserType!=3
        ORDER BY
        ec.cdate ASC