The problem of inserting null null values into a database table in asp.net

Insert operations on a table, such as two fields of datetime and int types, are allowed to be null.

With "sqlcmd." Parameters.Add ("@t12", tb12. Text) Parameter binding. DateTime type, TB12. Text is empty, insert success, do not error, view the value, but for 1900-01-01;int type, with the same statement, TB12. Text is empty, insert successful, do not error, view the value, but 0, with "sqlcmd." Parameters.Add (New SqlParameter ("@t12", Sqldbtype.datetime)); parameters["@t12"]. Value=tb12. Text; " Statement, TB12. Text is an empty insert and an error occurs.

sqlcmd.Parameters.Add(new SqlParameter("@t12",SqlDbType.DateTime));
if (tb12.Text.Length>0)
{
sqlcmd.Parameters["@t12"].Value=tb12.Text
}
else
{
sqlcmd.Parameters["@t12"].Value = System.DBNull.Value;
}