data binding - C#: How to adjust the value the user entered in DataGridView? -

I have a database datagrid view. Data source is a type of data that contains two dateTime columns (< Code> StartTimeStamp and EndTimeStamp ). I read and write the data in the SQL Server 2005 database using the update command of the typed data set.

The user should enter a date in each of the two columns, which I would like to use for the Selenelization and Rowlification I apply for However, I also need to make sure that the following two rules apply:

1. The time value for get started column should always be 00:00:00
for the end date column should always be 23:59:59 (or 11:59:59 pm if you wish)

As I do not want the user to enter 23:59:59 all the time, I somehow want to change the user's input 1 and 2. In my code

Where and how will I do this?

Edit

Sorry, if I was not clear, the user could enter any date part, though , Time portion for StartTimeStamp is fixed at midnight and for EndTimeStamp 23:59:59.

Example:

User enters the StartTimeStamp as of 01/01/01 01:00:00 PM. My application should change it 01/01/01 00:00:00.

As a user login, the end time stamp will be completed as of 01/01/2009 at 01:00. My application should change it 2009/01/31 23:59:59.