SQL连接语句简单操作

下面展示三种连接方式。

语法仅供参考

// 1，表链接
SELECT a.member_id,a.`name`,a.putYmd,a.city, b.ear_id, b.area
FROM member a JOIN earnings b
ON a.member_id = b.ear_id

//2，左连接
SELECT
	a.runoob_id,
	a.runoob_author,
	b.runoob_count 
FROM
	runoob_tbl a LEFT JOIN tcount_tbl b 
	ON a.runoob_author = b.runoob_author
	
//右链接
SELECT a.member_id,a.`name`,b.area,b.earnmonth
from member a RIGHT JOIN earnings b
on a.member_id = b.earnmonth and 
   b.singleincome>8 
   
//空值小记录
SELECT a.member_id,a.`name`,b.area,b.earnmonth
from member a RIGHT JOIN earnings b
on a.member_id = b.earnmonth and 
   b.singleincome>8 
	 and !ISNULL(a.member_id )