對於SQL查詢循環VB.net應用程序太快

Question

我正在設計使用Visual Basic與.Net 4.0與MS SQL服務器後端存儲數據的軟件。我爲數據庫的「員工工資」部分設計了一個類。這個類的子例程的目的是重置已經準備好的工資表。每次用戶「運行工資單」時，都會使用[SELECT * INTO]方法創建當前關聯表的備份。這部分通常工作得很好，沒有問題或問題。我遇到的問題是當我嘗試[重置]工資單時，[DROPS]「已修改」表並且再次使用[SELECT * INTO]方法從先前創建的備份中重新創建表。這是我寫的[RESET]代碼的示例。

Public Sub Reset_Payroll() 
    Dim conn As New SqlConnection() 
    conn.ConnectionString = _sqlConnector 

    Dim varSQL(4) As String 
    varSQL(0) = "DROP TABLE [EMPLOYEEWAGES]" 
    varSQL(1) = "DROP TABLE [EMPLOYEECHECKS]" 
    varSQL(2) = "DROP TABLE [EMPLOYEEREGISTAR]" 
    varSQL(3) = "DROP TABLE [EMPLOYEEPAY]" 

    For x As Integer = 0 To 3 
     Try 
      If conn.State = ConnectionState.Closed Then 
       conn.Open() 
      End If 
      Dim cmd As New SqlCommand(varSQL(x), conn) 
      cmd.ExecuteNonQuery() 
      Application.DoEvents() 
     Catch ex As Exception 
      MsgBox("PLEASE REPORT THIS MESSAGE TO CIS DEPT: " & ex.ToString, vbOKOnly, "STAFF WAGES [CREATE WAGES_TEMP] GENERAL EXCEPTION ERROR.") 
      'Utilities.CreateMessageAlert(_aspxPage, "PLEASE REPORT THIS MESSAGE TO CIS DEPT: " & ex.ToString, "strKey") 
      conn.Close() 
     End Try 
    Next 

    varSQL(0) = "SELECT * INTO [EMPLOYEEWAGES] FROM [EMPLOYEEWAGES_RUNCHK]" 
    varSQL(1) = "SELECT * INTO [EMPLOYEECHECKS] FROM [EMPLOYEECHECKS_RUNCHK]" 
    varSQL(2) = "SELECT * INTO [EMPLOYEEREGISTAR] FROM [EMPLOYEEREGISTAR_RUNCHK]" 
    varSQL(3) = "SELECT * INTO [EMPLOYEEPAY] FROM [EMPLOYEEPAY_RUNCHK]" 

    For x As Integer = 0 To 3 
     Try 
      If conn.State = ConnectionState.Closed Then 
       conn.Open() 
      End If 
      Dim cmd As New SqlCommand(varSQL(x), conn) 
      cmd.ExecuteNonQuery() 
      Application.DoEvents() 
     Catch ex As Exception 
      MsgBox("PLEASE REPORT THIS MESSAGE TO CIS DEPT: " & ex.ToString, vbOKOnly, "STAFF WAGES [CREATE WAGES_TEMP] GENERAL EXCEPTION ERROR.") 
      'Utilities.CreateMessageAlert(_aspxPage, "PLEASE REPORT THIS MESSAGE TO CIS DEPT: " & ex.ToString, "strKey") 
     Finally 
      conn.Close() 
     End Try 
    Next 

    varSQL(0) = "DROP TABLE [EMPLOYEEWAGES_RUNCHK]" 
    varSQL(1) = "DROP TABLE [EMPLOYEECHECKS_RUNCHK]" 
    varSQL(2) = "DROP TABLE [EMPLOYEEREGISTAR_RUNCHK]" 
    varSQL(3) = "DROP TABLE [EMPLOYEEPAY_RUNCHK]" 

    For x As Integer = 0 To 3 
     Try 
      If conn.State = ConnectionState.Closed Then 
       conn.Open() 
      End If 
      Dim cmd As New SqlCommand(varSQL(x), conn) 
      Application.DoEvents() 
      cmd.ExecuteNonQuery() 
     Catch ex As Exception 
      MsgBox("PLEASE REPORT THIS MESSAGE TO CIS DEPT: " & ex.ToString, vbOKOnly, "STAFF WAGES [CREATE WAGES_TEMP] GENERAL EXCEPTION ERROR.") 
      'Utilities.CreateMessageAlert(_aspxPage, "PLEASE REPORT THIS MESSAGE TO CIS DEPT: " & ex.ToString, "strKey") 
     Finally 
      conn.Close() 
     End Try 
    Next 

End Sub 

我有問題的區域是在代碼，其中該系統被重新創建，工資，支票，註冊器的所述第二部分，並從備份表[WAGES_RUNCHK]支付表。在前面的SQL查詢完成之前，似乎sql命令之間的for循環處理執行得太快。因此，一些表格不會從備份中重新創建，並且數據正在丟失。我添加了application.DoEvents（），但沒有投入生產。以前我不得不實施thread.sleep（）事件來嘗試給它一些時間來處理，但是我對這兩種解決方案都不滿意。

是否有任何方法或方法可以實現暫停，直到上一個查詢完成。允許系統與For循環中的SQL服務器進行通信： 「以前的查詢是否完成，如果是，則選擇[SELECT INTO]下一個查詢。我一直試圖讀取多線程處理，但仍然找到了一個舒適的解決方案。任何援助將不勝感激

Answer 1

我會做一個單一的存儲過程中的所有12個語句：。

CREATE PROCEDURE dbo.resetPayroll 
AS 
BEGIN 
    -- SET NOCOUNT ON added to prevent extra result sets from 
    -- interfering with SELECT statements. 
    SET NOCOUNT ON; 
    DROP TABLE [EMPLOYEEWAGES] 
    DROP TABLE [EMPLOYEECHECKS] 
    DROP TABLE [EMPLOYEEREGISTAR] 
    DROP TABLE [EMPLOYEEPAY] 
    SELECT * INTO [EMPLOYEEWAGES] FROM [EMPLOYEEWAGES_RUNCHK] 
    SELECT * INTO [EMPLOYEECHECKS] FROM [EMPLOYEECHECKS_RUNCHK] 
    SELECT * INTO [EMPLOYEEREGISTAR] FROM [EMPLOYEEREGISTAR_RUNCHK] 
    SELECT * INTO [EMPLOYEEPAY] FROM [EMPLOYEEPAY_RUNCHK] 
    DROP TABLE [EMPLOYEEWAGES_RUNCHK] 
    DROP TABLE [EMPLOYEECHECKS_RUNCHK] 
    DROP TABLE [EMPLOYEEREGISTAR_RUNCHK] 
    DROP TABLE [EMPLOYEEPAY_RUNCHK] 
END 

請注意，我的樣本存儲過程不包含任何錯誤捕獲或報告包裝在交易中這可能是一個非常好的主意。

然後您的代碼將成爲對數據庫的單個調用：

Dim cmd as New SqlCommand("resetPayroll", conn) 
cmd.CommandType = CommandType.StoredProcedure 
cmd.ExecuteNonQuery()