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我在更新数据表时遇到问题。我正在做的是这样的：

1）从数据库加载数据（我们称之为“旧数据库”

2）从其他数据库加载数据（我们称之为“新数据库”）

3）清除新数据库中的所有数据

4）将所有旧数据（来自旧数据库）合并到新数据库中

以下是我尝试完成此操作的方法：

        string oldDatabase = this.txtOldReport.Text;
        string newDatabase = this.txtNewReport.Text;
        string backupFolder = @"C:\Planit\Report Updater\Backups";

        if ( !Directory.Exists ( backupFolder ) ) {
            Directory.CreateDirectory ( backupFolder );
        }

        string fullPath = Path.Combine ( backupFolder, string.Format ( @"Update Backup_{0}_{1}_{2}_{3}_{4}_{5}",
                                                                       DateTime.Now.Year,
                                                                       DateTime.Now.Month,
                                                                       DateTime.Now.Day,
                                                                       DateTime.Now.Hour,
                                                                       DateTime.Now.Minute,
                                                                       DateTime.Now.Second) );

        Directory.CreateDirectory ( fullPath );

        File.Copy ( oldDatabase, Path.Combine ( fullPath, @"Old Report.mdb" ) );
        File.Copy ( newDatabase, Path.Combine ( fullPath, @"New Report.mdb" ) );

        OleDbConnection oldConnection = new OleDbConnection ( string.Format ( @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0}", oldDatabase ) );
        OleDbConnection newConnection = new OleDbConnection ( string.Format ( @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0}", newDatabase ) );
        OleDbCommand oldCommand = oldConnection.CreateCommand ( );
        OleDbCommand newSelectCommand = newConnection.CreateCommand ( );

        oldCommand.CommandText = @"SELECT * FROM Reports";
        newSelectCommand.CommandText = @"SELECT * FROM Reports";

        oldConnection.Open ( );
        newConnection.Open ( );

        DataSet oldDataset = new DataSet ( );
        DataSet newDataset = new DataSet ( );

        OleDbDataAdapter oldAdapter = new OleDbDataAdapter ( oldCommand );
        OleDbDataAdapter newAdapter = new OleDbDataAdapter ( newSelectCommand );

        OleDbCommandBuilder builder = new OleDbCommandBuilder ( newAdapter );

        builder.QuotePrefix = "[";
        builder.QuoteSuffix = "]";

        newAdapter.UpdateCommand = builder.GetUpdateCommand ( true );
        newAdapter.InsertCommand = builder.GetInsertCommand ( true );
        newAdapter.DeleteCommand = builder.GetDeleteCommand ( true );

        oldAdapter.Fill ( oldDataset );
        newAdapter.Fill ( newDataset );

        newDataset.Tables [ 0 ].Rows.Clear ( );

        // removed for a response below
        //foreach ( DataRow dr in newDataset.Tables [ 0 ].Rows ) {
        //    dr.Delete ( );
        //}

        foreach ( DataRow dr in oldDataset.Tables [ 0 ].Rows ) {
            dr.SetAdded ( );
            newDataset.Tables [ 0 ].ImportRow ( dr );
        }

        // removed for the response below
        //newDataset.AcceptChanges ( );

        newAdapter.Update ( newDataset.Tables [ 0 ] );

        oldConnection.Close ( );
        newConnection.Close ( );

    }

谁能看到我遇到的问题？当我调用“newAdapter.Update”时，什么也没有发生。

谢谢你的帮助。

4

1 回答 1

4

MSDN 说

调用 AcceptChanges 时，任何仍处于编辑模式的 DataRow 对象都会成功结束其编辑。DataRowState 也发生了变化：所有已添加和已修改的行变为未更改，删除的行被删除

所以，这条线

  newDataset.AcceptChanges ( );

从导入的表中删除添加的行状态，当您调用更新时，数据库中没有要添加的行，因为newDataset表中的每一行的状态等于Unchanged

所以你只需要删除它并再次调用你的newAdapter.Update

作为旁注，我认为您不需要遍历 newDataset.Tables[0] 来删除每一行，因为您newDataset.Tables[0].Rows.Clear()之前已经调用过

于 2013-10-29T15:46:45.287 回答