MySQL elt()函数

SELECT
        elt(
        INTERVAL ( c.load_percent,    0, 25, 50, 75, 100,2000),
        '0~25%', '25%~50%',    '50%~75%', '75%~100%',    '>100%'
        ) AS deviceId,
        count(c.id) AS loadPercent,
        data_date dataDate
        FROM
        table c
        GROUP BY
        data_date,
        elt(
        INTERVAL ( c.load_percent,    0, 25, 50, 75, 100,2000),
        '0~25%', '25%~50%',    '50%~75%', '75%~100%',    '>100%'
        )
limit #{offset},#{limit}

偷了懒，没有实现行专列的功能（ps：本来我的SQL水平就不怎么好，写的时候要么看教程，要么百度T，T）