我的mysql查询问题

Question

嘿伙计们，我有这个疑问：

SELECT Schwellwert
FROM lm_Schwellwert
WHERE (Typ = (SELECT Typ FROM lm_Artikel WHERE `Index` = (SELECT DISTINCT `Index` FROM lm_Warenkorb)))

但是当我运行它时，我收到了这个错误：

  

1242 - 子查询返回超过1行

我不知道我的查询中有什么错误。

lm_Schwellwert看起来的示例：

Typ     Schwellwert
Computer    78

lm_Artikel看起来的示例：

Index   Artikelbezeichnung  Status  Bestand     Lieferant    Typ
1           HP Elitebook        OK      19         HP         Computer     

lm_Warenkorb看起来的示例：

Index
11
1

Answer 1

条件只能在一个谷中运行（所以x = y等等） 在您的情况下，您的子查询

(SELECT Typ FROM lm_Artikel WHERE {索引{1}} {索引{1}}

返回多行，这会导致错误。

尝试修改您的查询，如下所示

= (SELECT DISTINCT

FROM lm_Warenkorb))运算符会对您有所帮助，因为接受一组值，如果SELECT Schwellwert FROM lm_Schwellwert WHERE (Typ IN (SELECT Typ FROM lm_Artikel WHERE `Index` IN (SELECT DISTINCT `Index` FROM lm_Warenkorb))) 等于其中一个值，则返回true

Answer 2

也许in会帮助您：

SELECT Schwellwert
FROM lm_Schwellwert
WHERE (Typ in (SELECT Typ FROM lm_Artikel WHERE `Index` in (SELECT DISTINCT `Index` FROM lm_Warenkorb)))

您还可以使用聚合函数min，例如：

SELECT Schwellwert
FROM lm_Schwellwert
WHERE (Typ in (SELECT min(Typ) FROM lm_Artikel WHERE `Index` in (SELECT min(`Index`) FROM lm_Warenkorb)))

Answer 3

试试这个

SELECT Schwellwert
FROM lm_Schwellwert
WHERE (Typ = (SELECT Typ FROM lm_Artikel 
              WHERE `Index` in (SELECT DISTINCT `Index` FROM lm_Warenkorb)))

因为你在索引中有两个值

Answer 4

SELECT DISTINCT `Index` FROM lm_Warenkorb

这个子查询返回两行..当你使用等号时，它应该只有一行..

试试这个：

SELECT Schwellwert
FROM lm_Schwellwert
WHERE (Typ = (SELECT  Typ FROM lm_Artikel WHERE `Index` in (SELECT DISTINCT `Index` FROM lm_Warenkorb)) limit 1)

Answer 5

尝试此查询

Select 
    lm_Schwellwert.Schwellwert
From lm_Schwellwert
Left join lm_Schwellwert as r 
    on r.Typ = (SELECT Typ FROM lm_Artikel WHERE `Index` = (SELECT DISTINCT `Index` FROM lm_Warenkorb))
Where r.id is not null  
group by lm_Schwellwert.Typ