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今天还有一个问题。这一次，我无法从 SQL Server CE 数据库中删除一行。

private void Form1_Load(object sender, EventArgs e)
{
        // Create a connection to the file datafile.sdf in the program folder
        string dbfile = new System.IO.FileInfo(System.Reflection.Assembly.GetExecutingAssembly().Location).DirectoryName + "\\userDtbs.sdf";
        SqlCeConnection connection = new SqlCeConnection("datasource=" + dbfile);

        // Read all rows from the table test_table into a dataset (note, the adapter automatically opens the connection)
        SqlCeDataAdapter adapter = new SqlCeDataAdapter("SELECT * FROM history", connection);
        DataSet data = new DataSet();
        adapter.Fill(data);

        //Delete from the database
        using (SqlCeCommand com = new SqlCeCommand("DELETE FROM accounts WHERE Id = 0", connection))
        {
            com.ExecuteNonQuery();
        }

        // Save data back to the databasefile
        var cmd = new SqlCeCommandBuilder(adapter);
        adapter.Update(data);

        // Close 
        connection.Close();
}

我的程序给了我一个错误，告诉我它connection处于关闭状态，我无法弄清楚为什么它会在DELETE命令执行之前关闭。

4

1 回答 1

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请注意：执行命令 withCommand.ExecuteXXX()需要先打开连接。将数据填充到DataSet使用SqlDataAdapter.Fill中不需要这样做，因为它在内部处理。执行SQL query这种方式是直接的，不需要任何Update方法调用adapter（因为您在删除后添加代码）。Update仅用于保存对您所做的更改DataSet。

    //Delete from the database
    using (SqlCeCommand com = new SqlCeCommand("DELETE FROM accounts WHERE Id = 0", connection))
    {
        if(connection.State == ConnectionState.Closed) connection.Open();
        com.ExecuteNonQuery();
    }
于 2013-08-25T04:10:49.113 回答