Question

Fill: SelectCommand.Connection 属性尚未初始化。

private DataSet ds = new DataSet();

private SqlConnection conn = null;

private SqlDataAdapter da = null;
// private SqlCommand cmd = null;

private const string DRIVER = "server=.;database=northwind;uid=sa;pwd=sa";

private const string sql_select = "select * from region";

/**/
/**

*
*
* * 此方法为将数据库northwind中的region表的数据查询出来并放入DataSet中

**/

private void Form1_Load(object sender, EventArgs e)
{

da = new SqlDataAdapter(sql_select, conn);

da.Fill(ds, "table");

this.dataGridView1.DataSource = ds.Tables["table"].DefaultView;
}

Answer 1

实例化一个Connection conn = new Connection(ConnectionText) ;
SelectCommand.Connection = conn ;
conn.Open() ;
SelectCommand.ExecuteNonQuery() ;
conn.Close() ;
或者;
Connection conn = new Connection(ConnectionText) ;
DataAdapter da= new DataAdapter() ;
DataAdapter.SelectCommand = new Command() ;
DataAdapter.SelectCommand.Connection = conn ;
DataAdapter.SelectCommand.CommandText = selecttext ;
DataSet ds = new DataSet() ;
da.Fill(ds) ;

Answer 2

private void Form1_Load(object sender, EventArgs e)
{
//connection使用前须初始化
conn =new SqlConnection(DRIVER );
da = new SqlDataAdapter(sql_select, conn);
da.Fill(ds, "table");
this.dataGridView1.DataSource = ds.Tables["table"].DefaultView;
}

还有问题追问或者HI 我~

Answer 3

MySqlConnection my2;
MySqlData ms2;