попробуйте это:
DataTable t = new DataTable();//in your case it's filled already like below or any other method
c.Open();
using (SqlCeDataAdapter a = new SqlCeDataAdapter("SELECT CO_COMP_ID as Company_Id,CO_COMP_NAME as Company_Name, CO_ACTIVE as Active_Status, CO_FILE_TYPE as Using_File_Type, CO_DESC as Description FROM CompRegister", c))
{
a.Fill(t);
//dgvCompDet.DataSource = t;
fnDeselectRow();
}
c.Close();
Предоставить таблицу данных в качестве источника данных для сетки данных
dgvCompDet.DataSource = t;