如何在 SQL 中从两个不同的表中选择值
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/8881713/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to select values from two different tables in SQL
提问by
I have two tables in my SQL Server database. The first is Test1and second is Test2. There is a column RegNoin both tables.
我的 SQL Server 数据库中有两个表。第一个是Test1，第二个是Test2。RegNo两个表中都有一列。
Now I want to select the values from both the tables for a particular RegNo.
现在我想从两个表中为特定的RegNo.
This is what I'm doing
这就是我正在做的
SELECT Test1.SurName, Test2.Class, Test2.Medium
FROM Test1,Test2 JOINS
Test2 ON Test1.RegNo = Test2.RegNo
But my query is giving error.
但我的查询给出了错误。
采纳答案by Eugen Rieck
SELECT Test1.SurName, Test2.Class, Test2.Medium
FROM Test1
INNER JOIN Test2 ON Test1.RegNo = Test2.RegNo
回答by
select
Test1.SurName,
Test2.Class,
Test2.Medium
from Test1
inner join Test2
on Test1.RegNo = Test2.RegNo
And if you want to select your data for a particular RegNo, just add a WHEREclause to the end, like so:
如果您想为特定的 选择数据RegNo，只需WHERE在末尾添加一个子句，如下所示：
select
Test1.SurName,
Test2.Class,
Test2.Medium
from Test1
inner join Test2
on Test1.RegNo = Test2.RegNo
where Test1.RegNo = 123456 -- or whatever value/datatype your RegNo is
回答by Taryn
SELECT Test1.SurName, Test2.Class, Test2.Medium
FROM Test1
INNER JOIN Test2
ON Test1.RegNo = Test2.RegNo
please see a visual explanation of joinsthis is very helpful in learning joins.
请查看连接的可视化说明，这对学习连接非常有帮助。
回答by Marco
Try this:
尝试这个：
SELECT Test1.SurName, Test2.Class, Test2.Medium
FROM Test1 INNER JOIN Test2
ON Test1.RegNo = Test2.RegNo
WHERE Test1.RegNo = desired_id
回答by Andreas Rohde
Very Basic question, try google next time and this now:
非常基本的问题，下次试试谷歌，现在试试：
SELECT Test1.SurName, Test2.Class, Test2.Medium
FROM Test1
inner join Test2 ON Test1.RegNo = Test2.RegNo
回答by Sam M
Here is your query with correction.
这是您的更正查询。
SELECT Test1.SurName, Test2.Class, Test2.Medium
FROM Test1 INNER JOIN Test2 ON Test1.RegNo = Test2.RegNo where Test2.RegNo=Test1.RegNo;
Also you can filter the query by providing the RegNo,on whichEver table u want.
您也可以通过提供您想要的 RegNo 来过滤查询。
回答by kontashi35
If you are looking foe method without join and relation.This will do the trick.
如果您正在寻找没有连接和关系的敌人方法。这将解决问题。
select
(
select s.state_name from state s where s.state_id=3
) statename,
(
select c.description from country c where c.id=5
) countryname
from dual;
where dual is a dummy table with single column--anything just require table to view
其中 dual 是一个带有单列的虚拟表——任何东西都只需要表来查看
