SQL，搜索真，假或两者

Question

我目前正在尝试编写可以返回TRUE，FALSE或NEITHER的SQL搜索代码。 虽然我目前拥有的代码可以使用，但是我不喜欢必须复制和粘贴大量代码这一事实，并且我想知道是否有一种方法可以减少此处的代码量。

DECLARE @FYear int = 2017
DECLARE @FQuarter char(2) = 'Q2'
DECLARE @FINANCIAL_GOAL_MET bit = NULL

IF(@FINANCIAL_GOAL_MET IS NULL)
    SELECT  FYear, 
            FQuarter, 
            IIF(FINANCIAL_GOAL_MET = 'TRUE', 1,0) AS Financial_Goal_Met
    FROM    Finances    
    WHERE   (FYear = @FYear) 
            AND (FQuarter = @FQuarter)
ELSE
    SELECT  FYear, 
            FQuarter, 
            IIF(FINANCIAL_GOAL_MET = 'TRUE', 1,0) AS Financial_Goal_Met
    FROM    Finances
    WHERE   (FYear = @FYear) 
            AND (FQuarter = @FQuarter)
            AND FINANCIAL_GOAL_MET = @FINANCIAL_GOAL_MET

Answer 1

您可以在一个查询中执行此操作：

DECLARE @FYear int = 2017;
DECLARE @FQuarter char(2) = 'Q2';
DECLARE @FINANCIAL_GOAL_MET bit = NULL;

SELECT FYear, FQuarter, 
       (CASE WHEN FINANCIAL_GOAL_MET = 'TRUE' THEN 1 ELSE 0
        END) AS Financial_Goal_Met
FROM Finances f  
WHERE (FYear = @FYear) AND (FQuarter = @FQuarter) AND
      (@FINANCIAL_GOAL_MET IS NULL OR FINANCIAL_GOAL_MET = @FINANCIAL_GOAL_MET);

对于不熟悉SQL Server中bit类型的用户，可以接受'TRUE'进行比较，即使它是字符串。