Sql server面试问题 [英] Sql server interview question

问题描述

I have attended an interview recently, and the interviewer asked me this question:

UserId  UserName
1          Name1
1          Name2
2          Name3
Here he wants me to retrieve either Name1 or Name2 using where condition?

How can I get the result?

I wrote like

select Username from Users where Username='Name1' or Username='Name2' 

but here both the conditions are satisfied so two records are coming... What will be the query to retrive the data?

我尝试了什么：

What I have tried:

select Username from Users where Username='Name1' or Username='Name2' 

推荐答案

hareesh babu写道：

hareesh babu wrote:

UserId用户名

< span class =code-digit> 1 名称1

1 名称2

2 Name3

UserId UserName
1 Name1
1 Name2
2 Name3

我想我会指出系统中存在不匹配。不应该有两个具有相同用户ID的用户，因此主键丢失/配置错误或者系统中存在一些灾难性故障。



如果密钥是就地（1,2或3），那么最好的选择可能是在WHERE子句中使用密钥。

I think I would have pointed out that there is a mismatch in the system. Two users having the same user ID shouldn't be possible so either the primary key is missing / configured in a wrong way or there is some catastrophic failure in the system.

If the keys would be in-place (1, 2, or 3) then probably the best option would be to use the key in the WHERE clause.

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