我如何加入三张桌子

Question

如何获取用户ID并检查是否与该用户有朋友。

SELECT * 
FROM wall 
inner join users on users.id=wall.Owner and request 
inner join users user.id=request.id 
ORDER BY wall.id_c DESC

Answer 1

如果我理解正确，可以尝试一下。

SELECT * 
FROM wall 
inner join users on users.id=wall.Owner 
join request on user.id=request.id 
ORDER BY wall.id_c DESC