Parametreler SQL sorgu açılan listesi

Question

Sonunda çalışmak için aşağıdaki kodu aldım. DDL'nin seçilen değerine göre farklı bir sorgu çalıştırır. Değil, en iyi yöntem ise. Her neyse, doğrudan aşağıdaki sorguda parametreler kullanarak nasıl giderim?

Ben parametreli dbname ve veritabanı kendisi mümkün olmak istiyorum. Teşekkürler.

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    if (DropDownList1.SelectedValue == "") 
    { 
     { 
      DataTable dt = new DataTable(); 
      GridView1.DataSource = dt; 
      GridView1.DataBind(); 
     } 
    } 
    if (DropDownList1.SelectedValue == "db1") 
    { 
     { 
      SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["db1ConnectionString"].ConnectionString); 
      SqlCommand cmd = new SqlCommand("select db1.dbo.table1.dbname where dbname = 'testdb1' ", con); 
      SqlDataAdapter Adpt = new SqlDataAdapter(cmd); 
      DataTable dt = new DataTable(); 
      Adpt.Fill(dt); 
      GridView1.DataSource = dt; 
      GridView1.DataBind(); 
     } 
    } 
    else if (DropDownList1.SelectedValue == "db2") 
    { 
     { 
      SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["db2ConnectionString"].ConnectionString); 
      SqlCommand cmd = new SqlCommand("select db2.dbo.table1.dbname where dbname = 'testdb2' ", con); 
      SqlDataAdapter Adpt = new SqlDataAdapter(cmd); 
      DataTable dt = new DataTable(); 
      Adpt.Fill(dt); 
      GridView1.DataSource = dt; 
      GridView1.DataBind(); 
     } 
    } 
} 

Answer 1

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    DataTable dt = new DataTable(); 
    SqlDataAdapter Adpt; 
    if(DropDownList1.SelectedValue == string.Empty) 
    { 
     //return; 
     //GridView1.DataSource = dt; 
     //GridView1.DataBind(); 
    } 
    if(DropDownList1.SelectedValue == "db1") 
    { 
     SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["db1ConnectionString"].ConnectionString); 
     SqlCommand cmd = new SqlCommand("select db1.dbo.table1.dbname where dbname = 'testdb1' ", con); 
     Adpt = new SqlDataAdapter(cmd); 
     new SqlDataAdapter(cmd).Fill(dt); 
    } 
    else if(DropDownList1.SelectedValue == "db2") 
    { 
     SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["db2ConnectionString"].ConnectionString); 
     SqlCommand cmd = new SqlCommand("select db2.dbo.table1.dbname where dbname = 'testdb2' ", con); 
     Adpt = new SqlDataAdapter(cmd); 
     new SqlDataAdapter(cmd).Fill(dt); 
    } 
    GridView1.DataSource = dt; 
    GridView1.DataBind(); 
}