- 联表查询,右边加限制条件,并且如果不满足该条件,右边内容为null的查询方式
- 错误的写法
SELECT t.*,n.id as news_log_id,n.user_id,n.status FROM `ad_news` as t left join ad_news_log as n ON t.id=n.news_id WHERE user_id=212617;
![](https://img.haomeiwen.com/i4467370/2fc97151e8421475.png)
- 正确的写法
SELECT t.*,n.id as news_log_id,n.user_id,n.status FROM `ad_news` as t left join ad_news_log as n ON t.id=n.news_id AND .n.user_id=212617;
![](https://img.haomeiwen.com/i4467370/0e7545810ca2ea86.png)
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