存储过程里的decimal(18,3) output，在c#里获得的时候却四舍五入了，成整数了。怎么处理

存储过程里的decimal(18,3) output，在c#里获得的时候却四舍五入了，成整数了。怎么办？

C# code

DbParameter BeginInAmount = db.GetDbParameter();        BeginInAmount.ParameterName = "@BeginInAmount";        BeginInAmount.DbType = DbType.Decimal;        BeginInAmount.Direction = ParameterDirection.Output;        list.Add(BeginInAmount);

C# code

BeginInAmount.DbType = DbType.Decimal;

SQL code

@BeginInAmount decimal(18, 3)