Question

准备一个应用程序，该应用程序将由本地网络上的本地SQL Server在办公室中的大约40个用户使用。在VB.NET中开发的应用程序。我已经阅读了一些文档，但希望直接从您这方面获得有关数据访问的一些知识。

这是一个Winforms应用程序，我想知道我使用的事务是否足以保护数据，例如当一个用户使用某些数据而另一个用户同时更改它时，事务是否会保护它？有人可以简要解释一下它是怎么回事吗？

我在我的应用程序中使用的SQL事务的示例

touchesEnded

Answer 1

根据您的商业规则，有两个版本 A）所有插入成功或全部失败。

Dim result As Boolean = True
Dim strcon = New AppSettingsReader().GetValue("ConnectionString", GetType(String))'.ToString()'no need. It is already **String**
Using connection As New SqlConnection(strcon)
  ''//--Following 2 lines are OK 
  ''//--Using cmd As New SqlCommand("INSERT INTO T_Sentence_SubSec_SecKatSubKat_SubSubKat (FK_Sentence_ID, FK_SubSec_SecKatSubKat_SubSubKat) VALUES (@FK_Sentence_ID, @FK_SubSec_SecKatSubKat_SubSubKat)", connection)
    ''//--cmd.CommandType = CommandType.Text
   ''//--but these two are better
   Using cmd As New SqlCommand("dbo.T_Sentence_SubSec_SecKatSubKat_SubSubKat_ins ", connection)
  ''//-- Insert aricle to Articles table (T_Artikel) and get inserted 
  ''//--row id to use it in other queries  
    cmd.CommandType = CommandType.StoredProcedure
   ''//-- Open generall connection for all the queries
    ''//--open connection in try block
    ''//--connection.Open()
    ''//-- Make the transaction.
    ''//--Dim transaction As SqlTransaction
    ''//--transaction = connection.BeginTransaction(IsolationLevel.ReadCommitted)
    Try
        connection.Open()
        cmd.Transaction = connection.BeginTransaction()
        cmd.Parameters.Add("@FK_Sentence_ID", SqlDbType.Int) ''//--or whatever
        cmd.Parameters.Add("@FK_SubSec_SecKatSubKat_SubSubKat", SqlDbType.Int)

       For Each sentId In pSentsId
           cmd.Parameters("@FK_Sentence_ID").Value = sentId
           cmd.Parameters("@FK_SubSec_SecKatSubKat_SubSubKat").Value =  SubSec_SecKatSubKat_SubSubKat
           cmd.ExecuteNonQuery() ''//--returns rows affected. We do not use result
        Next
        ''//--everything is OK
        cmd.Transaction.Commit()
    Catch ex as SqlException
       result = False
       ''//--SqlException is more informative for this case
       If cmd.Transaction IsNot Nothing
         cmd.Transaction.Rollback
         ''//--extra try...catch if you wish
       End If
    Catch ex As Exception
        result = False
        ''//-- Roll the transaction back.
        Try
            cmd.Transaction.Rollback()
        Catch ex2 As Exception
            ''// This catch block will handle any errors that may have occurred
            ''// on the server that would cause the rollback to fail, such as
            ''// a closed connection.
            ''//Console.WriteLine("Rollback Exception Type: {0}", ex2.GetType())
            ''//Console.WriteLine("  Message: {0}", ex2.Message)
        End Try
    Finally
      If connection.State <> Closed
        connection.Close()
      End If
    End Try
  End Using''//cmd
End Using''//connection
Return result

B）每个插入物都是独立的。不要使用整体交易。在try...catch循环内添加for。

多个SQL Server数据库访问

1 个答案: