04장 ADO.NET Web.Config 파일에 있는 섹션에 있는 값 가져오기

.ExecuteNonQuery() : 반환값이 없는 명령어 실행                                  Select문 이외의 명령어 실행시 사용 .ExecuteReader() : 다중 레코드(한개 이상의 레코드 반환) .ExecuteScalar() : 집계함수(AVG, Count)의 결과값 받고자 할 때,  즉, 단일 값 반환                                             ↕ using System; using System.Collections; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; public partial class FrmConfigurationManager : System.Web.UI.Page {     protected void Page_Load(object sender, EventArgs e)     {         //Web.Config 파일에 있는 <connectionStrings> 섹션에 있는 값 가져오기         string str = ConfigurationManager.ConnectionStrings                         ["ConnectionString"].ConnectionString;         Response.Write(str + "<br />");     } }

using System; using System.Collections; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; using System.Data.SqlClient; public partial class FrmExecuteScalar : System.Web.UI.Page {     protected void Page_Load(object sender, EventArgs e)     {         DisplayCategoryCount();         DisplayProductCount();     }     //등록된 상품 캣수     private void DisplayProductCount()     {         SqlConnection con = new SqlConnection                          (ConfigurationManager.ConnectionStrings                            ["ConnectionString"].ConnectionString);         con.Open();         SqlCommand cmd = new SqlCommand                                   ("Select Count(*) From Products", con);         //스칼라값 실행         this.lblProductCount.Text = cmd.ExecuteScalar().ToString();          con.Close();             }     //카테고리 상품 갯수     private void DisplayCategoryCount()     {         //DisplayProductCount();         SqlConnection conn = new SqlConnection                                         (ConfigurationManager.ConnectionStrings                                         ["ConnectionString"].ConnectionString);         conn.Open();         SqlCommand cmdd = new SqlCommand                                     ("Select Count(*) From Categories", conn);         //스칼라값 실행         this.lblCategoryCount.Text = cmdd.ExecuteScalar().ToString();          conn.Close();            } --다른 방식----------------------------------------------------------   using (SqlConnection con = new SqlConnection             (ConfigurationManager.ConnectionStrings              ["ConnectionString"].ConnectionString))         {             con.Open();             SqlCommand cmd = new SqlCommand(                 "Select Count(*) As Cnt From Categories",con);             SqlDataReader dr = cmd.ExecuteReader();             while (dr.Read())             {                 lblCategoryCount.Text = dr["Cnt"].ToString(); //카운터 출력             }         }

--파라미터 Prarameters 사용

↕ using System; using System.Collections; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; using System.Data.SqlClient; public partial class FrmParameters : System.Web.UI.Page {     protected void Page_Load(object sender, EventArgs e)     {     }     protected void btnSelect_Click(object sender, EventArgs e)     {         //[1]변수 선언부         string first = txtFirst.Text;         string second = txtSecond.Text;         //[2]커넥션         using (SqlConnection con = new SqlConnection(             ConfigurationManager.ConnectionStrings             ["ConnectionString"].ConnectionString))         {             con.Open();             //[3] 커맨드             SqlCommand cmd = new SqlCommand();             cmd.Connection = con;             cmd.CommandText =       //1. "Select *From Categories Where CategoryID Between 1 And 20";      //웹 텍스트박스에 15;Drop Table Message;-- 입력하면 테이블 삭제(위험)      //이와 같은 상황 보완하기 위해 3번 사용            //2. String.Format(@" Select *From Categories Where CategoryID       // Between {0} And {1}", first, second);           // 2번 같은 문을 사용하면, 웹사이트 상에서 어느 누구나 테이블 삭제 가능      // 그러므로 아래 3번과 같은 방식을 사용하여, 삭제 할 수 없도록 작성             //3. 마지막 제일 좋은 방식             "Select *From Categories Where CategoryID BetWeen                                 @First And @Second";             //파라미터 추가             cmd.Parameters.AddWithValue("@First", first); //Net 2.0             cmd.Parameters.AddWithValue("@Second", second);             //--------------------------------------------//             //cmd.Parameters.Add("@First",                       System.Data.SqlDbType.Int); //Net 1.X]             //cmd.Parameters["@First"].Value = second;             //--------------------------------------------//             // 생략 가능 cmd.CommandType = CommandType.Text;             //[4] 데이터 리더             SqlDataReader dr = cmd.ExecuteReader();                         //[5] 바인딩             ctlCategoryList.DataSource = dr;             ctlCategoryList.DataBind();                       //[6] 마무리             dr.Close();         }     } }