VB.net 应用程序对于 SQL 查询循环来说太快了

Question

我正在设计软件，使用 .Net 4.0 的 Visual Basic 和 MS SQL 服务器后端来存储数据。我为数据库的 "Employee Wages" 部分设计了一个 class。这个 Class 的子例程的目的是重置已经准备好的工资表。每次用户 "runs payroll" 它使用 [SELECT * INTO] 方法创建当前关联表的备份。这部分通常工作得很好，没有问题。我运行遇到的问题是当我尝试 [RESET] 工资单时，[DROPS] "modified" 表并再次使用 [SELECT * INTO] 方法重新创建来自先前创建的备份的表。这是我编写的 [RESET] 代码的示例。

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

我遇到问题的区域在代码的第二部分，系统正在从备份表 [WAGES_RUNCHK] 重新创建工资、支票、注册和支付表。看起来 sql 命令之间的 for 循环处理在前一个 SQL 查询完成之前执行得太快了。因此，一些表没有从备份中重新创建，数据正在丢失。我添加了 application.DoEvents() 但尚未投入生产。以前我必须实施 thread.sleep() 事件以尝试给它时间来处理，但我对这些解决方案中的任何一个都不满意。

是否有任何方法或方法可以实现暂停，直到上一个查询完成。允许系统在 For 循环中与 SQL 服务器通信： “上一个查询是否完成，如果是，那么 [SELECT INTO] 下一个查询。我一直在尝试阅读多线程处理，但仍然找到了一个舒适的解决方案。任何帮助将不胜感激。

Answer 1

我会制作一个包含所有 12 个语句的存储过程：

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

请注意，我的示例存储过程不包含任何错误捕获或报告。将其包装在交易中可能是一个非常好的主意。

您的代码将成为对数据库的单一调用：

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

VB.net 应用程序对于 SQL 查询循环来说太快了

VB.net application too fast for SQL query loop

vb.net

sql-server

.net-4.0