使用CASE T SQL表比较SQL

Question

我正在尝试编写一个表比较查询，当一行中的所有值都不相等时，它将返回通过/失败列。我有基本的语法，但它是传递/失败整个数据集，而不是特定的行。不知道是否需要在某处使用子查询。谢谢！

Actual Output: 
TestID LastName FirstName PrimaryLevel Result 
1   Smith  John   1   Fail 
2   Jones  Adam   2   Fail 
3   Barker  Bob   3   Fail 

Expected Output: 
TestID LastName FirstName PrimaryLevel Result 
1   Smith  John   1   Pass 
2   Jones  Adam   2   Fail 
3   Barker  Bob   3   Fail 

--Code: 
declare @TestID int 

declare @TestIDExpected varchar(max) 
declare @LastNameExpected varchar(max) 
declare @FirstNameExpected varchar(max) 
declare @PrimaryLevelExpected varchar(max) 

declare @TestIDActual varchar(max) 
declare @LastNameActual varchar(max) 
declare @FirstNameActual varchar(max) 
declare @PrimaryLevelActual varchar(max) 

set @TestID = 3 

set @TestIDExpected = (select TestID from ExpectedResults where TestID = @TestID) 
set @LastNameExpected = (select LastName from ExpectedResults where TestID = @TestID) 
set @FirstNameExpected = (select FirstName from ExpectedResults where TestID = @TestID) 
set @PrimaryLevelExpected = (select PrimaryLevel from ExpectedResults where TestID = @TestID) 

set @TestIDActual = (select TestID from ActualResults where TestID = @TestID) 
set @LastNameActual = (select LastName from ActualResults where TestID = @TestID) 
set @FirstNameActual = (select FirstName from ActualResults where TestID = @TestID) 
set @PrimaryLevelActual = (select PrimaryLevel from ActualResults where TestID = @TestID) 

select TestID, LastName, FirstName, PrimaryLevel, 
    case 
    when @TestIDExpected = @TestIDActual and @LastNameExpected = @LastNameActual and @FirstNameExpected = @FirstNameActual and @PrimaryLevelExpected = @PrimaryLevelActual then 'Pass' 
    else 'Fail' 
    END as Result from ActualResults 

Answer 1

我想你可以用普通的SQL来实现你所需要的。使用LEFT JOIN可以始终返回行，并填充TestResult列，并填充相应的值，指示是否找到匹配项。

如果只有两个表中的一行与TestID = 3那么结果将返回一行。您可以修改WHERE子句和您声明的变量值来满足您的需求。

声明变量和值：

DECLARE @TestID INT = 3; 

运行比较查询：

SELECT 
    a.TestID 
    , a.LastName 
    , a.FirstName 
    , a.PrimaryLevel 
    , CASE WHEN b.TestID IS NOT NULL THEN 'Pass' ELSE 'Fail END AS TestResult 
FROM 
    ActualResults a 
    LEFT JOIN ExpectedResults b ON 
    a.TestID = b.TestID 
    AND a.LastName = b.LastName 
    AND a.FirstName = b.FirstName 
    AND a.PrimaryLevel = b.PrimaryLevel 
WHERE 
    a.TestID = @TestID 

如果你想比较整个数据集，那么你就可以用WHERE条款沿降DECLARE声明：

SELECT 
    a.TestID 
    , a.LastName 
    , a.FirstName 
    , a.PrimaryLevel 
    , CASE WHEN b.TestID IS NOT NULL THEN 'Pass' ELSE 'Fail END AS TestResult 
FROM 
    ActualResults a 
    LEFT JOIN ExpectedResults b ON 
    a.TestID = b.TestID 
    AND a.LastName = b.LastName 
    AND a.FirstName = b.FirstName 
    AND a.PrimaryLevel = b.PrimaryLevel