myCommand.Parameters.Add("@GroNO", SqlDbType.Int);
myCommand.Parameters["@GroNO"].Value = "select GroNO from zb where grono = (select min(grono) from zb where flag<>2)";
@GroNO接受整型,但是你传的是字符串
myCommand.Parameters["@GroNO"].Value = "select GroNO from zb where grono = (select min(grono) from zb where flag<>2)";
Value 要赋值Int类型的、、、、