SQL Server : INSERT with a condition

Question

I want to insert into my Files-Favorites table only if the values I'm trying to pass isn't in there already.

I tried:

INSERT INTO [Files-Favorites](fileID,auditorID)  
     VALUES ('1', '34') 
      WHERE (fileID != '1' 
        AND auditorID != '34')

This doesn't work. I'm trying not to INSERT duplicate values. How do I pull this off? This is for a Microsoft SQL Server 2005.

Thank you

Answer 1

Try using if not exists

IF NOT EXISTS(SELECT * FROM [Files-Favorites] WHERE fileID = '1' AND auditorID = '34') 
BEGIN 
    INSERT INTO [Files-Favorites](fileID, auditorID) 
    VALUES('1', '34') 
END

Answer 2

我会使用一个复合（多列）键，而不是检查每个插入

ALTER TABLE [Files-Favorites] ADD CONSTRAINT unique_1 UNIQUE(fileID,auditorID)

Answer 3

We can use EXISTS with sub query to check the data existence and insert accordingly:

INSERT INTO [Files-Favorites](fileID,auditorID) 
SELECT fileID, auditorID FROM (
SELECT '1' fileID,'34' auditorID) t
WHERE NOT EXISTS(SELECT tm.fileID FROM [Files-Favorites] tm 
                 WHERE tm.fileID = t.fileID AND tm.auditorID = t.auditorID)