link

查联动数据,不需要把数据查出来在判断是否有关联,可以在查询时就直接判断有无关联

SELECT
    air_.id,
    air_.`name`,
    air_.orgz_code,
    analog_.id
FROM
    sb_airinfo_orgz air_
LEFT JOIN f_analog_link_air link_ ON link_.air_id = air_.id
LEFT JOIN b_analoginfo analog_ ON (
    analog_.id = link_.analog_id
    AND analog_.id = 16
)
WHERE
    air_.orgz_code LIKE "%1001%"

 id1不为null就是有关联,为null就是没有关联

原文地址:https://www.cnblogs.com/LcxSummer/p/15387033.html