Question

如何在SQL Server中使用此case语句？

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<div class="row" id="first-page">
  <div class = "row">
    <select id="animal">
      <option value = "bird">Bird</option>
      <option value = "cat">Cat</option>
      <option value = "Insect">Insect</option>
    </select>
  </div>
  <button class="btn waves-effect waves-light" id="continue-button">
    CONTINUE
  </button>
</div>

<div class="row" id="second-page">
  <div class = "row">
    <select id="animal-type">
      <option value = "hen">Hen</option>
      <option value = "lion">Lion</option>
      <option value = "butterfly">Butterfly</option>
    </select>
  </div>
</div>

如果这样的查询怎么办？

declare @isnot tinyint
select @isnot = 1

select top 100 * 
from Employee 
where EmployeeID > 1  
  and case 
         when @isnot = 1 
            then (EmployeeName = 'Brian') 
            else (EmployeeName = 'Anie')
end

我不想使用任何子查询或类似的东西。

Answer 1

declare @isnot tinyint
select @isnot = 1

SELECT top 100 * 
FROM Employee 
WHERE 
EmployeeID > 1  AND 
EmployeeName =
             CASE @isnot 
             WHEN 1 
             THEN 'Brian' 
             ELSE 'Anie'
             END

Answer 2

因为您正在使用值二进制检查（代码只关心值1或不是1），您还可以使用IIF来缩短语法。

DECLARE @isnot tinyint = 1

SELECT TOP 100 * 
FROM Employee 
WHERE EmployeeID > 1 AND
EmployeeName = IIF(@isnot = 1, 'Brian', 'Anie')

Answer 3

语法是关键，你需要END来完成CASE语句，而EmployeeName也开始了AND ...所以：

EITHER

SELECT TOP 100 * FROM Employee WHERE EmployeeID > 1
AND EmployeeName = CASE WHEN @isnot = 1 THEN 'Brian' ELSE 'Anie' END

OR

SELECT TOP 100 * FROM Employee WHERE EmployeeID > 1
AND EmployeeName = CASE WHEN @isnot = 1 THEN 'Brian' ELSE '' END

Answer 4

无案例陈述

WHERE EmployeeID > 1 
    AND (EmployeeName == 'Brian' AND @isnot = 1
        OR EmployeeName == 'Anie')

CASE语句添加到WHERE子句？

4 个答案: