根据另一个 WHERE(条件)选择要使用的 WHERE(Condition)

Question

我目前正在处理现有的数据透视表。我想根据(选择哪个(列值进行选择。要选择哪一列，它基于另一个条件。我举个例子：

@InputCharacter;
Select * from Table_A 
IF @InputCharacter  = 'a'
WHERE column_1 = 1 --Use this condition if @InputCharacter equal to a
ELSE IF @InputCharacter  = 'b'
WHERE column_2 = 1 --Use this condition if @InputCharacter equal to b
ELSE
WHERE column_3 = 1 --Use this condition if @InputCharacter equal to other value

我尝试在Web和Stackoverflow上搜索，但也许我不知道用于搜索的完美关键字，所以我来问这个问题。

Answer 1

我认为您可以使用OR或CASE

-- 1
SELECT *
FROM Table_A
WHERE (@InputCharacter = 'a' AND column_1 = 1)
   OR (@InputCharacter = 'b' AND column_2 = 1)
   OR (ISNULL(@InputCharacter,'') NOT IN ('a','b') AND column_3 = 1)
-- 2
SELECT *
FROM Table_A
WHERE
    CASE
      WHEN @InputCharacter = 'a' THEN IIF(column_1 = 1,1,0)
      WHEN @InputCharacter = 'b' THEN IIF(column_2 = 1,1,0)
      WHEN column_3 = 1 THEN 1
      ELSE 0
    END = 1
-- 3
SELECT *
FROM Table_A
WHERE
    CASE @InputCharacter
      WHEN 'a' THEN IIF(column_1 = 1,1,0)
      WHEN 'b' THEN IIF(column_2 = 1,1,0)
      ELSE IIF(column_3 = 1,1,0)
    END = 1