Select datetime column from SQL Server 2008 R2 table

Question

I have a DateTime column on a table in SQL Server 2008 R2 database. My c# front end is inserting a row in this table with a datetime parameter.

DateTime T = DateTime.Now;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "cargridsnapshot";
cmd.Parameters.AddWithValue("@t", T);
cmd.ExecuteNonQuery();

The datetime column in the row in the table is this:

2013-09-04 16:21:23.450

but

select * from table 
where TIMECOLUMN = '2013-09-04 16:21:23.450' 

returns no results.

Answer 1

SQL Server only stores time to approximately 1/300th of a second-you are probably using a value that cannot accurately be represented with the available bits.

Edit

You can check this behavior with the following code:

select CONVERT(DATETIME, '2013-09-04 16:21:23.450') -- returns 2013-09-04 16:21:23.450
select CONVERT(DATETIME, '2013-09-04 16:21:23.451') -- returns 2013-09-04 16:21:23.450
select CONVERT(DATETIME, '2013-09-04 16:21:23.452') -- returns 2013-09-04 16:21:23.453
select CONVERT(DATETIME, '2013-09-04 16:21:23.453') -- returns 2013-09-04 16:21:23.453
select CONVERT(DATETIME, '2013-09-04 16:21:23.454') -- returns 2013-09-04 16:21:23.453
select CONVERT(DATETIME, '2013-09-04 16:21:23.455') -- returns 2013-09-04 16:21:23.457

Bottom line

Don't try to identify rows with a datetime...

Answer 2

What if you use this

Select * from table where convert(date,yourcolumn)=convert(date,your_datetime)

but kindly note it will compare on date only

Answer 3

SQL Server can represent datetime in a variety of ways when comparing a string to your database value. Some have the month before the day, some day before month. The localization of your SQL Server is causing your issue; you can read more about it here . Specifically, look for SET DATEFORMAT .

Answer 4

The SQL Server datetime type is accurate only only to increments of .000 , .003 , or .007 seconds.

So when you save a value with .450 , that will be fine. But if you saved with .451 , that would get rounded back down to .450 , and then it wouldn't match up.

You can avoid this by using a datetime2 column type.

Also - you probably shouldn't be storing DateTime.Now in your database. Read here .