SQL 使用一张表中的 where 选择多行
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SQL Select multiple rows using where in one table
提问by Munkhjin
I have a table named "Student".
我有一个名为“学生”的表。
Student
id | name | age
1 | john | 10
2 | Hyman | 10
3 | jerry| 10
I wanna select 1 and 2 rows. I wrote that Select * from Student where name=john and name=HymanBut return "Empty Set".
How do i do it. Help me.
我想选择 1 和 2 行。我写了Select * from Student where name=john and name=Hyman但返回“空集”。我该怎么做。帮我。
回答by
select *
from student
where name in ('john', 'Hyman')
Or
或者
select *
from student
where name = 'john'
or name = 'Hyman'
回答by MatBailie
You need an ORrather than an AND.
你需要一个OR而不是一个AND.
Whatever conditions your write, it checks them all against each record. As no single record has both name = 'john'AND name = 'Hyman'they all fail.
无论您的写入条件如何，它都会根据每条记录检查它们。由于没有一条记录同时具有name = 'john'ANDname = 'Hyman'它们都失败了。
If, instead, you use OR...
- The 1st record yields TRUE OR FALSEwhich is TRUE.
- The 2nd record yields FALSE OR TRUEwhich is TRUE.
- The 3rd record yields FALSE OR FALSEwhich is FALSE.
相反，如果您使用OR...
- 第 1 条记录产生的TRUE OR FALSE结果为 TRUE。
- 第二条记录产生的FALSE OR TRUE结果是 TRUE。
- 第 3 条记录的收益FALSE OR FALSE率为 FALSE。
Select * from Student where name='john' OR name='Hyman'
Or, using a differnt way of saying it all...
或者，用不同的方式来表达这一切......
SELECT * FROM Student WHERE name IN ('john', 'Hyman')
回答by Russell
Use single quotes to surround your values, plus use and instead of or:
使用单引号将您的值括起来，并使用 and 代替 or：
where name='john' or name = 'Hyman'
回答by Tamkeen
try this one.
试试这个。
declare @names varchar(100)
set @names='john,Hyman'
Select * from Student
where charIndex(',' + rtrim(cast(name as nvarchar(max))) + ',',',' +isnull(@names,name) +',') >0
