使用sql从两个表的表中检索数据 [英] To retrieve data from table of two tables using sql

问题描述

亲爱的所有人，



查找表格

Dear All,

Find the tables

VNumbers
(
VNumber nvarchar(max), 
Amount nvarchar(max)
) 

Submittable
(
Snumber nvarchar(max), 
Amount nvarchar(max)
)

VNumbers已经拥有reords如下

VNumbers is already having reords as below

VNumber | Amount
1001    | 100
1002    | 100
1003    | 100
1004    | 100

SubmitTable为空。现在在Snumber字段中的SubmitTable中插入值1001以从VNumbers表中检索金额（100）。



但是以下查询无效。请回复我，下面的查询中哪里有错误，还有其他方法吗？

SubmitTable is empty. Now inserting value 1001 in SubmitTable in Snumber field to retrieve amount (100) from VNumbers table.

But below query is not working. Please reply me, where is mistake in below query and is there another way?

select VNumbers.amount from VNumbers inner join submitTable on VNumbers.VNumber=submitTable.VNumber where VNumbers.VNumber=1001

推荐答案

您正在使用 VNumbers.VNumber = submitTable.VNumber加入两个表 with INNER JOIN 。只要两个表中的列之间存在匹配，INNER JOIN关键字就会选择两个表中的所有行。您可以使用 LEFT JOIN 连接两个表。

LEFT JOIN关键字返回左表中的所有行（VNumbers），即使有右表中没有匹配（SubmitTable）

阅读本文le b / b


SQL LEFT JOIN





VNumbers.VNumber = submitTable.VNumber

应更正为

VNumbers.VNumber = submitTable.SNumber

[/ EDIT]

You are joining both tables using VNumbers.VNumber=submitTable.VNumber with INNER JOIN.The INNER JOIN keyword selects all rows from both tables as long as there is a match between the columns in both tables.you can use LEFT JOIN to connect both tables.
The LEFT JOIN keyword returns all the rows from the left table (VNumbers), even if there are no matches in the right table (SubmitTable)
Read this article

SQL LEFT JOIN


VNumbers.VNumber=submitTable.VNumber
should be corrected as
VNumbers.VNumber=submitTable.SNumber
[/EDIT]

查看这个...

Hi,

Check this one...

SELECT V.amount from VNumbers V, submitTable S
WHERE S.Snumber=V.VNumber and S.Snumber=1001
--or V.Vnumber=1001

您的查询中的字段名称似乎是submitTable.VNumber。









我希望这会对你有所帮助。





干杯

It seems to be wrong field name in your query as "submitTable.VNumber".




I hope this will help you.


Cheers

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