public IEnumerable <TEntityType> GetAll()
{
string classtype = typeof(TEntityType).Name;
string cmd = $"select * from {classtype}";
var dt = SqlHelpers.GetDataTable(_connection, cmd);
for (int i = 0; i < dt.Rows.Count; i++)
{
yield return(_mapper.ConvertToEntity(dt.Rows[i]));
}
}