mysql查询索引，删除索引

#查询表的索引
SHOW INDEX FROM  表名称
#删除表的索引
DROP INDEX STREET ON 表名称（字段）;

#实时数据
where dateTime>=(NOW() - interval 24 hour)
#七天的数据
WHERE dateTime >= date_sub(curdate(), interval 7 day)
#当日的日期函数
where date = date_sub(curdate(), interval 2 day)
#
interval是减法的意思

case when的用法

SELECT 
    CASE
    WHEN 字段名 = '1' THEN '自住'
    WHEN HOUSE_TYPE = '2' THEN '租住'
    WHEN HOUSE_TYPE = '3' THEN '投亲靠友'
    WHEN HOUSE_TYPE = '4' THEN '酒店'
    WHEN HOUSE_TYPE = '5' THEN '民宿'
    WHEN HOUSE_TYPE = '6' THEN '宿舍'
    WHEN HOUSE_TYPE = '7' THEN '工棚'
    WHEN HOUSE_TYPE = '8' THEN '其他'
    END as `name`,
    count(1) `value`
    FROM
    t_dws_dt_yd_tianfu_healthy_communication
    WHERE STREET = '条件'
    GROUP BY name

另外一种写法

SELECT
    CASE
    WHEN HOUSE_TYPE = '1' THEN '自住'
    WHEN HOUSE_TYPE = '2' THEN '租住'
    WHEN HOUSE_TYPE = '3' THEN '投亲靠友'
    WHEN HOUSE_TYPE = '4' THEN '酒店'
    WHEN HOUSE_TYPE = '5' THEN '民宿'
    WHEN HOUSE_TYPE = '6' THEN '宿舍'
    WHEN HOUSE_TYPE = '7' THEN '工棚'
    else '其他'
    END as name,
    count(1) value
    FROM
    t_dws_dt_yd_tianfu_healthy_communication
    WHERE STREET = #{street}
    GROUP BY name
    ORDER BY value DESC