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Insert empty DateTime from C# into FoxPro

I am trying to insert an empty DateTime into a FoxPro database using DbParameter in C#. Our application marries FoxPro data along with SQL Server and .NET models/data.
My current issue is that most of our DateTime types in C# are not nullable, nor should they be. However, most of our legacy data in FoxPro are empty dates (shown as ' / / : : '). I am trying to do an insert into the FoxPro table where I do a check to see if the .NET DateTime meets certain criteria, then inserts an empty date. This last part has proven to be a nightmare.
What I have tried so far:
.Parameters.Add(string.Empty, new DateTime())
The above understandably inserts 01/01/0001 but is not what we want.
.Parameters.Add(string.Empty, "{}")
.Parameters.Add(string.Empty, "{:://}")
.Parameters.Add(string.Empty, "{//}")
.Parameters.Add(string.Empty, "'{}'")
The above all result in
System.Data.OleDb.OleDbException: 'Data type mismatch'.
which makes sense because I'm trying to send a string to a field with DateTime type.
Does anyone know how to insert an empty DateTime into FoxPro?

If I'm understanding you correctly, you're not using a DbParameter, but rather an OleDbParameter, and you're adding them through the OleDbParameterCollection.Add method?
If so, consider that you are using the overload that is .Add(String, Object), and you could instead use the overload that is .Add(String, OleDbType):
.Parameters.Add(string.Empty, OleDbType.Date)
The default value of an OleDbParameter is null, so you don't need to do anything more for your empty dates.
Also, depending on how the column is defined in your FoxPro database schema, it may be appropriate to pass OleDbType.Date, OleDbType.DBDate, OleDbType.DBTime, or OleDbType.DBTimeStamp. The full list of OleDB types is documented here, but I'm not entirely certain how they align to FoxPro's data types.

I believe your second example is close, but you have the Date and Time portions reversed.
It should be .Parameters.Add(string.Empty, "{//::}")
The // represent the Date portion, and the :: the Time portion.

Not sure of your SQL-Insert statement for VFP, but you MAY need to adjust it and do TWO different inserts. One IF a date exists, another if it does not.
For the one that does NOT have a date, I would hard-enter the following (for example where the "?" are the parameter place-holders)
insert into yourTable ( fld1, fld2,..., YourDateField ) values ( ?, ?, ..., ctot('') )
the function CTOT() means character to datetime and an empty string will comply with expected VFP Date/time field.

Work for me.
Parameters.AddWithValue("CreateDate", new DateTime(1899,12,30,0,0,0));

Datetime format is 'mm-dd-yyyy' when getting while using SqlDataAdapter but if I run the same query in ms sql then its 'yyyy-mm-dd'

I know the question is a bit confusing. Please let me elaborate.
Suppose
I have a table student master which has a column DOB
I have inserted a record and in DOB I have inserted '1991-01-01'
running select statement from sql server is returning date in the same format as it is inserted '1991-01-01' but when I am running the same query from C# using SqlDataAdapter then its returning date as '01-01-1991'
Can anyone explain why it is happening and is there any way to fetch the date in same format as it is inserted.
Query
Is it possible to get the DateTime using SqlDataAdapter as it was inserted?
P.S: column data type is Datetime

let's separate the wheat from the chaff :)
if for your needs meaningful is data type (datetime in this case), then formatting does not matter at all. All layers which will exchange or process the data will use data type information for that.
But
if the meaningful part is formatting, i.e. string representation of the data, then you need to consider the appropriate settings of UI tools you use to display your data. SSMS, for example, uses regional settings for that. If you need to visualize data in the identical manner, so you need the identical strings, you should take care of formatting by your self or in another words, you need to convert your datetime data to string in the same way in all places where you need it.
In T-SQL, for example, you could use CAST and CONVERT functions for formatting your data in a format you need.

If you can't match up the "Cultures" between the SQL Server and the machine you're building the application on (and, in fact, you cannot rely on that really if you're application is going to be deployed to other machines!), then the cheap and quick way round it is to run your date returns through a parse function such as this:
private string FncFormatDate(string date)
{
DateTime formattedDate;
if (DateTime.TryParse(date, out formattedDate))
{
return formattedDate.ToString("yyyy-MM-dd");
}
else
{
return "Invalid date";
}
}
I hope this answers your question.

How to retrieve Timestamp value from SQL Server using DataReader

How to retrieve Timestamp value(eg:0x000000048E18B9D8 ) from SQL Server using DataReader? I'm getting an IndexOutOfRangeException when doing like this
DateTime date = reader.GetDateTime(reader.GetOrdinal("Timestamp"));
Can anyone help on this?
Also I want to know how to pass timestamp parameter to stored procedure using .Net code

IndexOutOfRangeException thrown on reader.Getordinal() suggests that a column called Timestamp doesn't exist. Check your column names again, and replace with the actual value. By default, it will be called timestamp, but only if you haven't specified a column name.
You could also try string ts = reader["timestamp"].toString(), and make sure it returns something.
According to MSDN, a TIMESTAMP data type is "8 bytes...[and]... just an incrementing number and does not preserve a date or a time. To record a date or time, use a datetime data type."
Therefore, reader.GetInt64() is probably close, if you really need this value, but byte[] myTimestamp = reader["timestamp"] is probably better.
As far as passing it back to your stored procedure, you can create a new parameter with SqlDbType.Timestamp. The value will be a byte array, or, if you have it stored as a string, you could try something like:
cmd.Parameters.Add("#TimeStampParam", SqlDbType.Timestamp).Value = System.Text.Encoding.ASCII.GetBytes(myTimestampStr);`
(NB: I haven't tested this, but it should be close enough).
Note that TIMESTAMP is deprecated, and ROWVERSION is not the preferred syntax.

c# SQL Server : DATETIME datatype

I am writing a unit test which stores an object with a DateTime parameter into a DATETIME2 SQL Server database column. I then create a temporary DateTime object called new_date_time and set that value to DateTime.Now.
The new_date_time value is then used to update the previous value and the SQL query to do this completes successfully.
When re-reading the object back from the database I receive the correct datetime values for days/hours/minutes but the .Ticks value is different from the new_date_time variables .Ticks property. The value returned from the read call returns the last 4 digits of the .Ticks property as zeros.
Why is this rounding occurring making my Assert.AreEqual fail?? :)
Thanks

I guess you are using Parameters.AddWithValue when writing the date to Sql Server. From MSDN the inferred type of a CLR DateTime is SqlDbType.DateTime and not SqlDbType.DateTime2 so the precision is being lost when writing your date to the database.
Explicitly setting the type to datetime2 will solve the issue. For example:
command.Parameters.AddWithValue("#now", DateTime.Now).SqlDbType =
SqlDbType.DateTime2;
Edit
#marc_s makes a good point with his comment:
You should read (and embrace!) Can we stop using AddWithValue() already?
To avoid these kind of issues from biting you, you could get into the habit of using the Add method on the parameters collection which takes the SqlDbType in some overloads and then set the Value property on that rather than using the AddWithValue method:
command.Parameters.Add("#now", SqlDbType.DateTime2).Value = DateTime.Now;

Maybe your database field is not storing your entire DateTime.Now value, because it's not precise enough. Why don't you simply compare your dates after you've formatted them as you like?
eg: (untested):
var databaseDate = d1.ToString("MM/dd/yyyy HH:mm:ss.fff");
var tempDate = d2.ToString("MM/dd/yyyy HH:mm:ss.fff");
Assert.AreEqual(databaseDate, tempDate);
I tested: using Linq To Entities My DateTime.Now is correctly saved to my datetime2(7) and equality test return True.
Are you sure you're passing your correct datetime value to the database? without truncating it?

Error in inserting statement when inserting

I am working on c# project and using winform.
Here the problem is the query was working previously but now it is not working
Here the todaydate is a datetimePicker which is set to short date format
and my datatype of column is smalldatetime the error i am getting is
The conversion of a nvarchar data type to a
smalldatetime data type resulted in an out-of-range value.
The statement has been terminated.
if i have two date time picker one for date and second for time then how can i insert? please can you guide me

AddWithValue determines the datatype of the parameter from the value you pass.
In your case you are passing a string and thus the parameter is passed to the database as a string not as a datetime expected by the database
you should change that line
cmd.Parameters.AddWithValue("#today", todaydate.Value);

You're currently passing in the text value, which means something else is having to then parse it as a date. Don't do that. Given that you've got a DateTimePicker, you should just use the DateTime value it provides:
cmd.Parameters.AddWithValue("#today", todaydate.Value);
... or create the parameter first with a specific type (SqlDbType.SmallDateTime), then set the value using todaydate.Value. The important point is to avoid the string conversion.
Wherever possible, you should avoid converting values into text. Keep them in their "natural" form (e.g. DateTime in this case) for as much of the time as possible: on input, parse into the natural form, and if you can avoid ever converting to a string, do so!

I think your time7 column in database is smalldatetime and you tried to assign it a string. I don't suggest it.
Try with Add() method like this;
command.Parameters.Add("#today", SqlDbType.SmallDatetime);
command.Parameters["#today"].Value = todaydate.Value;
or you can use AddWithValue() as also like this;
cmd.Parameters.AddWithValue("#today", todaydate.Value);