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我正在使用 VS 2010 同步 2 个数据库（SQL Express 和 SQL Compact Edition）。程序首次运行时它工作正常。但是，当代码执行多次时，会出现 SQL 命令“超时”异常。错误信息是：

超时已过。在操作完成之前超时时间已过或服务器没有响应。

以下是我处理ClientInsertServerInsert冲突的代码。（编辑：根据这篇 MSDN 文章，这与客户端和服务器都插入具有相同主键值的行有关。这会导致主键冲突。）

    Dim conflictTableName As String = e.TableMetadata.TableName.ToString
    Dim serverConflictDT, clientConflictDT As DataTable
    Dim clientConflictID As Int16
    Dim new_ID As Int16
    Dim SqlCon As New SqlConnection
    clientConflictDT = e.Conflict.ClientChange
    serverConflictDT = e.Conflict.ServerChange

    If e.Conflict.ConflictType = ConflictType.ClientInsertServerInsert Then
        SqlCon = New SqlConnection(STR_SQL_CON)

        Using SqlCon
            If SqlCon.State = ConnectionState.Closed Then SqlCon.Open()
            MsgBox(SqlCon.PacketSize.ToString & vbNewLine & conflictTableName.ToString)
            Dim sqlStr = "SELECT CASE WHEN MAX(ID) IS NULL THEN 0 ELSE MAX(ID)+1 END               FROM " & conflictTableName

            Dim sqlcmd As New SqlCommand(sqlStr, SqlCon)
            sqlcmd.CommandTimeout = 2

            new_ID = sqlcmd.ExecuteScalar  '<- This is the line where the Exception occurred

            clientConflictID = clientConflictDT.Rows(0)(0)

            MsgBox(new_ID.ToString & conflictTableName.ToString)

            Try
                Using SqlCeCon As New SqlCeConnection(STR_SQLCE_CON)
                    If SqlCeCon.State = ConnectionState.Closed Then SqlCeCon.Open()

                    Dim sqlCeCmd As New SqlCeCommand
                    Dim sqlCeStr = Nothing

                    sqlCeStr = "SELECT CASE WHEN MAX(ID) IS NULL THEN 0 ELSE MAX(ID)+1 END FROM " & conflictTableName
                    sqlCeCmd = New SqlCeCommand(sqlCeStr, SqlCeCon)
                    If new_ID < sqlCeCmd.ExecuteScalar Then
                        new_ID = sqlCeCmd.ExecuteScalar
                    End If

                    sqlCeStr = "UPDATE " & conflictTableName & " SET id=" & new_ID & " WHERE id=" & clientConflictID
                    sqlCeCmd.CommandText = sqlCeStr
                    sqlCeCmd.ExecuteNonQuery()
                End Using
            Catch ex As Exception

            Finally

            End Try

        End Using


    End If

提前致谢

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1 回答 1

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我想这是由数据库锁引起的。在我修改 SQL SELECT 语句之后

"SELECT CASE WHEN MAX(ID) IS NULL THEN 0 ELSE MAX(ID)+1 END FROM " & conflictTableName

至

"SELECT CASE WHEN MAX(ID) IS NULL THEN 0 ELSE MAX(ID)+1 END FROM " & conflictTableName & " WITH (NOLOCK)"

然后问题解决了。

无论如何，感谢所有评论:-)

于 2012-06-05T02:55:28.737 回答