how to insert datetime into the SQL Database table?

DateTime values should be inserted as if they are strings surrounded by single quotes:

'20100301'

SQL Server allows for many accepted date formats and it should be the case that most development libraries provide a series of classes or functions to insert datetime values properly. However, if you are doing it manually, it is important to distinguish the date format using DateFormat and to use generalized format:

Set DateFormat MDY --indicates the general format is Month Day Year

Insert Table( DateTImeCol )
Values( '2011-03-12' )

By setting the dateformat, SQL Server now assumes that my format is YYYY-MM-DD instead of YYYY-DD-MM.

SET DATEFORMAT

SQL Server also recognizes a generic format that is always interpreted the same way: YYYYMMDD e.g. 20110312.

If you are asking how to insert the current date and time using T-SQL, then I would recommend using the keyword CURRENT_TIMESTAMP. For example:

Insert Table( DateTimeCol )
Values( CURRENT_TIMESTAMP )

if you got actuall time in mind GETDATE() would be the function what you looking for

You will need to have a datetime column in a table. Then you can do an insert like the following to insert the current date:

INSERT INTO MyTable (MyDate) Values (GetDate())

If it is not today's date then you should be able to use a string and specify the date format:

INSERT INTO MyTable (MyDate) Values (Convert(DateTime,'19820626',112)) --6/26/1982

You do not always need to convert the string either, often you can just do something like:

INSERT INTO MyTable (MyDate) Values ('06/26/1982') 

And SQL Server will figure it out for you.