常用SQL

• 单表根据某字段去重，保留主键ID最小一条。需要移除SQL_MODEL中的ONLY_FULL_GROUP_BY。通过SELECT @@SQL_MODE;命令查看。

-- 移除wm_im_notice_i表中other_id重复的并且保留ID最小的行。
DELETE
FROM
    `wm_im_notice_i`
WHERE
    `other_id` IN(
    SELECT
        other_id
    FROM
        (
        SELECT
            `other_id`
        FROM
            `wm_im_notice_i`
        GROUP BY
            `other_id`
        HAVING
            COUNT(*) > 1
    ) AS t1
) AND id NOT IN(
    SELECT
        id
    FROM
        (
        SELECT
            MIN(id) AS id
        FROM
            `wm_im_notice_i`
        GROUP BY
            `other_id`
        HAVING
            COUNT(*) > 1
    ) AS t2
)

•  连表更新

-- eg 左连接
UPDATE wm_im_notice_i AS i
        LEFT JOIN
    wm_im_notice_h AS h ON h.im_cus_code = i.im_cus_code 
SET 
    i.im_notice_id = h.notice_id