问题描述

我有一个基本的 SQL 查询，开头是:

I have a basic SQL query, starting with:

SELECT top 20 application_id, [name], location_id FROM apps

现在，我想完成它以便它做到这一点(用伪代码编写)

Now, I would like to finish it so that it does this (written in Pseudocode)

if @lid > 0 then
    WHERE location_id IN (@lid)
else
    WHERE location_id is all values in location_id column

<小时>

根据要求，这是一个例子

As requested, here is an example

application_id             name               location_id
----------------------------------------------------------
1                          Joe Blogs          33
2                          Sam Smith          234
3                          Jeremy Carr        33

@locid 是用户给出的结果，例如'33, 234'

@locid is the results given by the user, for example '33, 234'

如果@lid 为空，那么我希望它输出带有名称和application_id 的location_id 的所有行.否则，我希望它输出与@lid 中提供的数字相关的所有行(代表 location_id.

If @lid is empty then I'd like it to output all rows for location_id with name and application_id. Otherwise, I'd like it to output all rows in relation to the provided numbers in @lid (standing for location_id.

所以，如果@lid 为 0:

So, if @lid is 0:

application_id             name               location_id
----------------------------------------------------------
1                          Joe Blogs          33
2                          Sam Smith          234
3                          Jeremy Carr        33

否则，如果@lid 包含'33'

Otherwise, if @lid contains '33'

application_id             name               location_id
----------------------------------------------------------
1                          Joe Blogs          33
3                          Jeremy Carr        33

推荐答案

尝试使用 Case，它用于 IIF 或三元运算符.请检查此链接 http://msdn.microsoft.com/en-us/图书馆/ms181765.aspx

Try using Case, which serves the purpose of an IIF or a ternary operator. Please check this link http://msdn.microsoft.com/en-us/library/ms181765.aspx

干杯

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