According to your query
Select * from [User] U where U.DateCreated = '2014-02-07'
SQL Server is comparing exact date and time i.e (comparing 2014-02-07 12:30:47.220
with 2014-02-07 00:00:00.000
for equality). that's why result of comparison is false
Therefore, While comparing dates you need to consider time also. You can use
Select * from [User] U where U.DateCreated BETWEEN '2014-02-07' AND '2014-02-08'
.