oledb，視覺狐狸親和c＃

Question

我有視覺狐狸親數據庫與成千上萬的行。我正在使用oledb從fox pro獲取數據並導出（在完成一些計算和格式化之後）到sql server.I曾使用數據集一次填充2-3個數據表（相關表）。

第一個問題是內存使用非常高，因爲數據集很大。我想減少內存佔用。對此有任何建議。

所以我已經決定在time.How獲取幾行做我使用OLEDB命令，這樣我就可以根據所有獲取的如1-20和20-40再等

Answer 1

讀取行這裏的評論和HatSoft的代碼就是我認爲你正在尋找的東西。這是僞代碼，這意味着它不會編譯，但應該給你一個從這裏開始的好主意。

int NumberOfRecordsToRetrieve = 10000; 
int StartRecordNumber = 1; 
bool EndOfFile = false; 

string queryString = "SELECT OrderID, CustomerID FROM Orders WHERE RECNO() BETWEEN @StartRecordNumber AND @EndRecordNumber"; 

While (!EndOfFile) 
{ 
    using (OleDbConnection connection = new OleDbConnection(connectionString)) 
    { 
     OleDbCommand command = new OleDbCommand(queryString, connection); 
     command.Parameters.Add(new OleDbParameter("@StartRecordNumber", StartRecordNumber)); 
     command.Parameters.Add(new OleDbParameter("@EndRecordNumber", StartRecordNumber + NumberOfRecordsToRetrieve)); 

     connection.Open(); 
     OleDbDataReader reader = command.ExecuteReader(); 

      EndOfFile = true; 
      while (reader.Read()) 
      { 
       EndOfFile = false 

       //Retrieve records here and do whatever process you wish to do 
      } 
      reader.Close(); 

      StartRecordNumber += NumberOfRecordsToRetrieve; 
    } 
} 

Answer 2

string queryString = "SELECT OrderID, CustomerID FROM Orders WHERE ORDERID >= @StartOrderID AND ORDERID <= @EndOrderID"; 

    using (OleDbConnection connection = new OleDbConnection(connectionString)) 
    { 
     OleDbCommand command = new OleDbCommand(queryString, connection); 
     command.Parameters.Add(new OleDbParameter("@StartOrderID", "PASS THE VALUE HERE")); 
     command.Parameters.Add(new OleDbParameter("@EndOrderID", "PASS THE VALUE HERE")); 

     connection.Open(); 
     OleDbDataReader reader = command.ExecuteReader(); 

     while (reader.Read()) 
     { 
//Retrieve records here 
     } 
     reader.Close(); 
    }