如何正確編寫INSERT子查詢？

Question

我測試了SQL的每個部分，它工作正常。

的東西是錯誤與我WHERE條款然而..沒有得到太多細節在VS 2012但是設置斷點...

如何來代碼的INSERT語句使用MS SQL Server的一個子查詢？

INSERT INTO Emails (email, insertDate) 
VALUES (@Email, @DateToday) 
WHERE NOT EXISTS (SELECT Emails.email 
        FROM Emails WHERE Emails.email = @Email); 

Answer 1

INSERT INTO Emails (email, insertDate) 
SELECT @Email, @DateToday 
WHERE NOT EXISTS (SELECT Emails.email 
        FROM Emails WHERE Emails.email = @Email); 

Answer 2

這將工作

INSERT INTO Emails (email, insertDate) 
SELECT @Email, @DateToday 
WHERE NOT EXISTS (SELECT Emails.email 
        FROM Emails WHERE Emails.email = @Email) 

但更好的解決方案可能對電子郵件列的唯一索引

Answer 3

嘗試使用類似以下內容：

"INSERT INTO Emails (email, insertDate) VALUES ('@Email', '@DateToday') WHERE NOT EXISTS (SELECT Emails.email FROM Emails WHERE Emails.email = '@Email');" 

Answer 4

INSERT INTO Emails (email, insertDate) 
SELECT Email, DateToday 
WHERE NOT EXISTS (SELECT Emails.email 
        FROM Emails WHERE Emails.email = Email) 

它將工作集email作爲非空列或唯一索引。