我不知道我的查询有什么不对

Question

SELECT *,
(SELECT * 
 FROM regions WHERE regions.RID=registration.REGION) as region_out 
FROm registration

  

1241 - 操作数应包含1列

Answer 1

SELECT r1.*, r2.*
FROM registration r1,
INNER JOIN regions r2 ON ( r2.RID=r1.REGION )

Answer 2

子查询只能返回一个值，因此您无法SELECT *。这是错误消息告诉你的内容。您只能选择一个列或值。

Answer 3

你写得更好：

SELECT registration.*, regions.* 
FROM regions 
join registration on regions.RID=registration.REGION;

Answer 4

试试这个：

SELECT * FROM registration
LEFT JOIN regions ON (regions.RID=registration.REGION);