Question

我有一个连接数据库的类并执行查询

public class dbConnect
{
    public MySqlConnection Connection { get; set; }
    public MySqlCommand cmd;

...

public void Connetti()
    {
        try
        {
            if (Connection.State == ConnectionState.Closed)
            {
                Connection.Open();
            }
        }

        catch (Exception ex)
        {
            MessageBox.Show("Errore " + ex.Message);
        }

    }

如何返回MySqlCommand cmd？

public void SetQuery(string sSQL)
    {
        MySqlCommand cmd = new MySqlCommand(sSQL, Connection);
        //return cmd.ExecuteReader();
    }

}

让MySqlCommand实例返回是有用的，用于datatable.Load =＆gt; dt.Load（cmd.ExecuteReader（））;

public MainWindow()
    {
        InitializeComponent();

        conn.Connetti();

        //MySqlCommand cmd = new MySqlCommand("SELECT * FROM tb_navi Order By NOMENAVE", conn.Connection);                        conn.SetQuery("SELECT * FROM tb_navi Order By NOMENAVE");

        System.Data.DataTable dt = new System.Data.DataTable();
        //dt.Load(cmd.ExecuteReader());
        dt.Load(conn.cmd);   //now cmd is null
        dtGrid.DataContext = dt; 

    }

Answer 1

从您的方法中返回已填充的DataTable：

public DataTable SetQuery(string sSQL)
{
    DataTable dt = new DataTable();
    using (MySqlCommand cmd = new MySqlCommand(sSQL, Connection))
    {
        _cmd.ExecuteNonQuery();

        using (MySqlDataAdapter da = new MySqlDataAdapter(cmd))
        {
            da.Fill(dt);
        }
    }
    return dt;
}

Answer 2

试试这个

public DataTable GetTableData(string StrSQL)
    {
        DataTable dataTable = new DataTable();
        MySqlCommand mySqlCommand = null;
        MySqlDataReader mySqlDataReader = null;
        try
        {


                mySqlCommand = new MySqlCommand(StrSQL, Connection);                    
                mySqlDataReader = mySqlCommand.ExecuteReader();
                dataTable.TableName = "mydata";
                dataTable.Load(mySqlDataReader);                    

        }
        finally
        {
            if (mySqlDataReader != null)
            {
                if (!mySqlDataReader.IsClosed)
                {
                    mySqlDataReader.Close();
                }
            }
        }
        return dataTable;
    }

C＃查询操作

2 个答案: