此行已属于此表

Question

我从以下代码收到错误“此行已属于此表”：

public static DataTable AddNewAllocations(string pCaseNo, ref DataTable pTable)
    {
        try
        {
            string sqlText = "SELECT UserID FROM tblUsers;";
            aSqlQuery aQ = new aSqlQuery(sqlText, "table");
            DataTable userTable = aQ.TableResult;

            foreach (DataRow userRow in userTable.Rows)
            {
                int allocAlready = 0;
                foreach (DataRow allocRow in pTable.Rows)
                {
                    if (allocRow["FeeEarner"].ToString() == userRow["UserID"].ToString())
                    {
                        allocAlready = 1;                            
                    }
                }
                if (allocAlready == 0)
                {
                    string strUser = userRow["UserID"].ToString();          
                    decimal fees = cTimesheet.UserFees(strUser, pCaseNo);
                    int intCaseNo = Int32.Parse(pCaseNo);
                    if (fees > 0)
                    {
                        Object[] array = new object[8];
                        array[0] = 0;
                        array[1] = intCaseNo;
                        array[2] = DateTime.Today;
                        array[3] = strUser;
                        array[4] = fees;
                        array[5] = 0;
                        array[6] = fees;
                        array[7] = true;
                        pTable.Rows.Add(array);
                    }
                }
            }
            return pTable;
        }

        catch (Exception eX)
        {
            throw new Exception("cAllocation: Error in NewAllocations()" + Environment.NewLine + eX.Message);
        }

当我逐步执行代码时，我可以看到第二次抛出错误，访问以下行：

pTable.Rows.Add(array);

鉴于每次代码进入循环时我都会创建一个新的对象数组，我不明白为什么我会收到此错误消息，这表明多次添加同一行。当每次由新对象数组生成行时，为什么代码将每个循环视为添加相同的数据行？

Answer 1

另一种方法是在循环开始时创建一个 NewRow()，分配其数据，然后在循环底部创建 Rows.Add()。

{       
        // initialization code 
        // ...

        foreach (DataRow row in dt.Rows)
        {
            row.Delete();
        }
        Oda.Update(ds, "USERTABLE");

        DataRow  dr;

        foreach (var userRecord in urList)
        {
            dr = dt.NewRow();
            dr["username"] = userRecord.userName;
            dr["firstname"] = userRecord.firstName;
            dr["lastname"] = userRecord.lastName;
            dr["createdon"] = userRecord.createdOn;

            dt.Rows.Add(dr);
        }
        Oda.Update(ds, "USERTABLE");
}