如何根據參數在SELECT中設置字段的值？

Question

我想什麼是有一個選擇設置一個稱爲電流場的基於表的值和兩個變量，都聲明爲輸入存儲過程與選擇的值如下：

DECLARE @AdminTestId INT = 111 
DECLARE @UserTestId INT = null 
AdminTestId  UserTestId  Current 
111        1 
111        1 
222        0 
333        0 

DECLARE @AdminTestId INT = 111 
DECLARE @UserTestId INT = 457 
AdminTestId  UserTestId  Current 
111    456   0 
111    457   1 
123        0 

一些幫助和建議，將不勝感激。

Answer 1

看起來你已經有了一些邏輯，其中當前才應該設置爲1，如果UserTestId爲空或UserTestId列相匹配。你可以在你的SQL查詢中使用case語句，如下所示：

DECLARE @AdminTestId INT = 111 
DECLARE @UserTestId INT = 457 

SELECT 
    AdminTestId, 
    UserTestId 
    CASE 
    WHEN (@AdminTestId IS NULL AND @UserTestId IS NULL) THEN 0 
    WHEN (@AdminTestId = AdminTestId AND @UserTestId = UserTestId) THEN 1 
    WHEN (@AdminTestId = AdminTestId AND @UserTestId IS NULL) THEN 1 
    WHEN (@AdminTestId IS NULL AND @UserTestId = UserTestId) THEN 1 
ELSE 0 
END AS IsCurrent 

Answer 2

SELECT 
    ... 
    CAST(CASE 
    WHEN t.AdminTestID = @AdminTestID 
     AND (t.UserTestID = @UserTestID 
     OR @UserTestID is NULL AND t.UserTestID is NULL) 
    THEN 1 
    ELSE 0 
    END as bit) as Current 
FROM ...