[英]SQL - Select rows from two different tables
有这张桌子
Table "Items"
itemID
itemTitle
itemContent
和这个
Table "MyList"
userID
itemID
deleted
如果给定用户ID,即使“MyList”中不存在itemID,如何从表“Items”中选择所有行并显示“已删除”字段?
查询结果示例:
itemID | itemTitle | deleted | userID
-------------------------------------
1 | Title1 | 1 | 2
2 | Title2 | 0 | 2
3 | Title3 | (null) | (null)
4 | Title4 | (null) | (null)
什么是查询,以便我可以得到那个结果?
谢谢
SELECT I.itemID, I.itemTitle, M.deleted
FROM
Items I
LEFT OUTER JOIN MyList M ON M.itemID = I.itemID
WHERE M.userID = 9
编辑:基于OP的评论:
SELECT I.itemID, I.itemTitle, M.deleted, M.userID
FROM
MyList M
LEFT OUTER JOIN Items I ON I.itemID = M.itemID
WHERE M.userID = 9
您可以使用outer join
:
select a.itemId, a.itemTitle, b.deleted
from Items a left outer join MyList b
on a.itemId = b.itemId
我不确定这是否是最好的方法,但它会返回我想要的内容:
select itemID, itemTitle, deleted, userID
FROM(
SELECT i.id_itemID, i.itemTitle, M.deleted, M.userID
FROM
MyList M
right OUTER JOIN Items I ON I.itemID= M.itemID
) as MyTableItems
where itemID = 3 or itemID is null
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