使用C更新數據庫中的字段時遇到問題＃

Question

我正在嘗試編寫一個程序，該程序將表中的某個GUID更改爲用戶指定的GUID。 問題是當它試圖用新的覆蓋舊的GUID它將給我以下錯誤：

You cannot add or change a record because a related record is required in table tblEF

該數據庫有5個表。主表tblA的主鍵設置爲pkAccounts。其他表都有一個外鍵，稱爲fkAccounts。

所有關係都設置爲實施參照完整性和級聯刪除相關記錄。如果我手動打開數據庫並編輯關係以具有Cascade Update Related Fields，我的程序將更新GUID，但數據庫所用的程序將不再起作用。

試圖克服這一點，我添加到將放棄主鍵在主表上的變量，然後在程序完成替換所有GUID後添加主鍵。在這種情況下，我將得到Alter表中的語法錯誤

這是我的代碼。對不起，如果它是凌亂的，但這是我的第一個程序之一。加上我第一次搞亂SQL的東西。

try 
{ 
    string GetRI = "SELECT fkAccountGUID FROM tblR"; 
    string GetTWI = "SELECT pkAccountGUID FROM tblTW"; 
    string GetAI = "SELECT pkAccountGUID FROM tblA"; 
    string GetEAI = "SELECT fkAccountGUID FROM tblEAI"; 
    string GetEF = "SELECT fkAccountGUID FROM tblEF"; 
    string NoPK = "ALTER TABLE tblA DROP CONSTRAINT pkAID"; 
    string PK = "ALTER TABLE tblA ADD PRIMARY KEY (pkAID)"; 

    DataSet ds = new DataSet(); 

    //create a connection to the database 
     OleDbConnection ConnectDatabase = new OleDbConnection(
      "Provider=Microsoft.Jet.OLEDB.4.0;" + 
      @"Data Source=C:\db.mdb;" + 
      "Persist Security Info=True;" + 
      "Jet OLEDB:Database Password=123;"); 

    //open the connection to the database 
    ConnectDatabase.Open(); 

    //creates an adapter and runs the string command from the database connection 
    //it will then fill the information in the dataset in its own table 
    OleDbDataAdapter DatabaseAdapter = new OleDbDataAdapter(GetRI, ConnectDatabase); 
    DatabaseAdapter.Fill(ds, "tblR"); 
    OleDbDataAdapter DatabaseAdapter1 = new OleDbDataAdapter(GetAI, ConnectDatabase); 
    DatabaseAdapter.Fill(ds, "tblA"); 
    OleDbDataAdapter DatabaseAdapter2 = new OleDbDataAdapter(GetTWI, ConnectDatabase); 
    DatabaseAdapter.Fill(ds, "tblTW"); 
    OleDbDataAdapter DatabaseAdapter3 = new OleDbDataAdapter(GetEAI, ConnectDatabase); 
    DatabaseAdapter.Fill(ds, "tblEAI"); 
    OleDbDataAdapter DatabaseAdapter4 = new OleDbDataAdapter(GetEF, ConnectDatabase); 
    DatabaseAdapter.Fill(ds, "tblEF"); 

    //get old GUID 
    Console.WriteLine("What is the current GUID?"); 
    string OldGUID = Console.ReadLine(); 
    char ap = '\x0027'; 
    OldGUID = ap + OldGUID + ap; 

    //get new GUID 
    Console.WriteLine("What is the new GUID name?"); 
    string NewGUID = Console.ReadLine(); 
    NewGUID = ap + NewGUID + ap; 

    //test lines 
    //Console.WriteLine(NewGUID); 
    //Console.WriteLine(OldGUID); 

    //UPDATE string to rename the old GUID to the New GUID 
    string UpdateR = "UPDATE tblR SET fkAccountGUID=" + NewGUID + "WHERE fkAccountGUID=" + OldGUID; 
    string UpdateA = "UPDATE tblA SET pkAccountGUID=" + NewGUID + "WHERE pkAccountGUID=" + OldGUID; 
    string UpdateTW = "UPDATE tblTW SET pkfkAccountGUID=" + NewGUID + "WHERE pkfkAccountGUID=" + OldGUID; 
    string UpdateEA = "UPDATE tblTW SET fkAccountGUID=" + NewGUID + "WHERE fkAccountGUID=" + OldGUID; 
    string UpdateEF = "UPDATE tblEF SET fkAccountGUID=" + NewGUID + "WHERE fkAccountGUID=" + OldGUID; 

    //create the variables to run the string commands 
    OleDbCommand updatecmd0 = new OleDbCommand(UpdateF); 
    OleDbCommand updatecmd1 = new OleDbCommand(UpdateR); 
    OleDbCommand updatecmd2 = new OleDbCommand(UpdateEA); 
    OleDbCommand updatecmd3 = new OleDbCommand(UpdateTW); 
    OleDbCommand updatecmd4 = new OleDbCommand(UpdateA); 
    OleDbCommand nocheckcmd = new OleDbCommand(NoPK); 
    OleDbCommand checkcmd = new OleDbCommand(PK); 

    //have the commands connect to the database 
    nocheckcmd.Connection = ConnectDatabase; 
    updatecmd0.Connection = ConnectDatabase; 
    updatecmd1.Connection = ConnectDatabase; 
    updatecmd2.Connection = ConnectDatabase; 
    updatecmd3.Connection = ConnectDatabase; 
    updatecmd4.Connection = ConnectDatabase; 
    checkcmd.Connection = ConnectDatabase; 

    //Run the commands 
    nocheckcmd.ExecuteNonQuery(); 
    updatecmd0.ExecuteNonQuery(); 
    updatecmd1.ExecuteNonQuery(); 
    updatecmd2.ExecuteNonQuery(); 
    updatecmd3.ExecuteNonQuery(); 
    updatecmd4.ExecuteNonQuery(); 
    checkcmd.ExecuteNonQuery(); 

    //Dispose the adapter and close the connection to the database. 
    DatabaseAdapter.Dispose(); 
    ConnectDatabase.Close(); 

    //console will display the string if everything completed 
    Console.WriteLine("Success. Press any key to exit."); 
    Console.Read(); 

} 
catch (OleDbException Error) 
{ 
    //when an error occurs display the error in the console 
    Console.WriteLine(Error.Message); 
    Console.Read(); 
} 

基本上，我怎麼編輯5數據庫中的GUID字段，而手動打開數據庫檢查級聯更新，運行我的程序，然後重新打開數據庫，並取消選中級聯更新？

Answer 1

而不是刪除約束，只需向表中添加一個新行並複製數據即可。

1. 用用戶想要的GUID插入一個新行。
2. 然後使用舊行的數據更新該行。
3. 更改爲新行的所有外鍵引用
4. 刪除舊行

Answer 2

添加一個名爲「UserEnteredGuid」一欄，並顯示給用戶，而不是真正 GUID每當值不爲空。這真的是唯一的理智方法。

通常，主鍵將是永遠不會被修改的值。