クエリのTips

SELECT 
    type
   ,group_concat(item_id separator ',') as item_list
FROM
    item_mst
WHERE
    start_date < NOW()
AND
    (end_date IS NULL OR NOW() < end_date)
GROUP BY
    type

SELECT
    *
FROM
    log_tbl
WHERE
    DATE_FORMAT(reg_date, '%Y%m%d') = '20151102'

SELECT
    *
FROM
    log_tbl
WHERE
    LEFT(reg_date, 10) = '2015-11-02'