if not exists in sql server code example

Example 1: if exists sql server

IF EXISTS (SELECT * FROM tblGLUserAccess WHERE GLUserName ='xxxxxxxx') 
BEGIN
   SELECT 1 
END
ELSE
BEGIN
    SELECT 2
END

Example 2: sqlite insert if not exists

#id column is assumed to be primary key

INSERT INTO destination_table(id,name) 
SELECT id, name
FROM source_table s
WHERE NOT EXISTS (
  SELECT 1
  FROM destination_table d
  WHERE d.id = s.id
);

Example 3: if not exists in sql

At first glance your original attempt seems pretty close. I'm assuming that clockDate is a DateTime fields so try this:

IF (NOT EXISTS(SELECT * FROM Clock WHERE cast(clockDate as date) = '08/10/2012') 
    AND userName = 'test') 
BEGIN 
    INSERT INTO Clock(clockDate, userName, breakOut) 
    VALUES(GetDate(), 'test', GetDate()) 
END 
ELSE 
BEGIN 
    UPDATE Clock 
    SET breakOut = GetDate()
    WHERE Cast(clockDate AS Date) = '08/10/2012' AND userName = 'test'
END 
Note that getdate gives you the current date. If you are trying to compare to a date (without the time) you need to cast or the time element will cause the compare to fail.

If clockDate is NOT datetime field (just date), then the SQL engine will do it for you - no need to cast on a set/insert statement.

IF (NOT EXISTS(SELECT * FROM Clock WHERE clockDate = '08/10/2012') 
    AND userName = 'test') 
BEGIN 
    INSERT INTO Clock(clockDate, userName, breakOut) 
    VALUES(GetDate(), 'test', GetDate()) 
END 
ELSE 
BEGIN 
    UPDATE Clock 
    SET breakOut = GetDate()
    WHERE clockDate = '08/10/2012' AND userName = 'test'
END 
As others have pointed out, the merge statement is another way to tackle this same logic. However, in some cases, especially with large data sets, the merge statement can be prohibitively slow, causing a lot of tran log activity. So knowing how to logic it out as shown above is still a valid technique.