一.測試連接是否成功

//String str = "server=(local);database=MyDb;uid=asp;pwd=asp";String str = "server=.;database=MyDb;uid=asp;pwd=asp";SqlConnection conn = new SqlConnection(str);conn.Open();Response.Write(conn.State);

二.增刪改實現

代碼實踐：

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Data.SqlClient;namespace demo01 {public partial class SqlCommandOne : System.Web.UI.Page{protected void Page_Load(object sender, EventArgs e){}//新增protected void Button1_Click(object sender, EventArgs e){string str = "server=.;database=mydb;uid=asp;pwd=asp";SqlConnection conn = new SqlConnection(str);conn.Open(); //記得打開;//創建命令對象;SqlCommand cmd = new SqlCommand();cmd.CommandText = "insert student values(4,'王帥',19,'男',1)";//指定的是cmd的要執行的sql語句cmd.Connection = conn;//命令對象與哪個連接對象關聯;//要執行了;int result = cmd.ExecuteNonQuery();if (result > 0)Response.Write("增加數據成功!");elseResponse.Write("增加數據失敗!");//最后需要關閉連接對象conn.Close();}protected void btnDel_Click(object sender, EventArgs e){string str = "server=.;database=mydb;uid=asp;pwd=asp";SqlConnection conn = new SqlConnection(str);conn.Open(); //記得打開;//創建命令對象;SqlCommand cmd = new SqlCommand();//from可以省略，但是一般不省略；cmd.CommandText = "delete student where stuid=1";//指定的是cmd的要執行的sql語句cmd.Connection = conn;//命令對象與哪個連接對象關聯;//要執行了;int result = cmd.ExecuteNonQuery();if (result > 0)Response.Write("刪除數據成功!");elseResponse.Write("刪除數據失敗!");//最后需要關閉連接對象conn.Close();}protected void btnEdit_Click(object sender, EventArgs e){string str = "server=.;database=mydb;uid=asp;pwd=asp";SqlConnection conn = new SqlConnection(str);conn.Open(); //記得打開;//創建命令對象;SqlCommand cmd = new SqlCommand();cmd.CommandText = "update student set deptId=1,stuName='王亞亞' where stuId=3";//指定的是cmd的要執行的sql語句cmd.Connection = conn;//命令對象與哪個連接對象關聯;//要執行了;int result = cmd.ExecuteNonQuery();if (result > 0)Response.Write("修改數據成功!");elseResponse.Write("修改數據失敗!");//最后需要關閉連接對象conn.Close();}} }

三.參數化的增刪改實踐

參考代碼：

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; //引用命名空間; using System.Data.SqlClient;namespace demo01 {public partial class SqlCommandTwo : System.Web.UI.Page{protected void Page_Load(object sender, EventArgs e){}protected void btnAdd_Click(object sender, EventArgs e){//定義了一個變量，來表示連接數據庫的字符串;string str = "server=.;database=mydb;uid=asp;pwd=asp";SqlConnection conn=new SqlConnection(str);conn.Open();//命名對象,由conn創建，就不用寫連接屬性了;SqlCommand cmd = conn.CreateCommand();//cmd.CommandText = "insert student values(5,'胡魯瓦',8,'男',1)";//cmd.CommandText = "insert student values("+txtStuId.Text+",'胡魯瓦',8,'男',1)"; 不拼接了string gender=RadioButton1.Checked?"男":"女";//StringBuilder,追加;String sql = string.Format(@"insert student values({0},'{1}',{2},'{3}',{4})",txtStuId.Text,txtStuName.Text,txtAge.Text,gender,txtDeptID.Text);cmd.CommandText = sql;//執行int result = cmd.ExecuteNonQuery();if (result > 0)Response.Write("成功");elseResponse.Write("失敗");//關閉conn.Close();}protected void btnEdit_Click(object sender, EventArgs e){//定義了一個變量，來表示連接數據庫的字符串;string str = "server=.;database=mydb;uid=asp;pwd=asp";SqlConnection conn = new SqlConnection(str);conn.Open();//命名對象,由conn創建，就不用寫連接屬性了;SqlCommand cmd = conn.CreateCommand();//獲取數據;string gender = RadioButton1.Checked ? "男" : "女";//**************************SqlCommand的參數化設置，比較流行;//sql語句的變化 String sql = "update student set stuName=@stuName,age=@age,gender=@gender,deptid=@deptId where stuId=@stuId";//@stuId等，是動態參數;需要我們給它賦值;cmd.CommandText = sql;//SqlCommand,有參數化的屬性;//Add("動態參數",值);cmd.Parameters.Add("@stuId",txtStuId.Text.Trim());cmd.Parameters.Add("@stuName", txtStuName.Text.Trim());cmd.Parameters.Add("@age", txtAge.Text);cmd.Parameters.Add("@gender", gender);cmd.Parameters.Add("@deptId", txtDeptID.Text.Trim());//**************************//執行int result = cmd.ExecuteNonQuery();if (result > 0)Response.Write("成功");elseResponse.Write("失敗");//關閉conn.Close();}} }

四.聚合函數查詢

參考代碼：

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Data.SqlClient;namespace demo01 {public partial class selectOne : System.Web.UI.Page{protected void Page_Load(object sender, EventArgs e){}protected void btnSelectAll_Click(object sender, EventArgs e){//定義了一個變量，來表示連接數據庫的字符串;string str = "server=.;database=mydb;uid=asp;pwd=asp";SqlConnection conn = new SqlConnection(str);conn.Open();//命名對象,由conn創建，就不用寫連接屬性了;SqlCommand cmd = conn.CreateCommand();//查看總條數的命令語句//string sql = "select count(*) from student";string sql = "select MIN(age),max(age) from student";cmd.CommandText = sql;//執行查詢只能得到第一行，一列的值;返回類型：object-->int //int num = Convert.ToInt32(cmd.ExecuteScalar());//int num = (int)cmd.ExecuteScalar();string num = (String)cmd.ExecuteScalar();Response.Write("最小年齡：" + num);}} }

五.查詢所有學生信息顯示到頁面

參考代碼如下：

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Data.SqlClient; using System.Data; using System.Text; //擴充namespace demo01 {public partial class selectTwo : System.Web.UI.Page{protected void Page_Load(object sender, EventArgs e){}protected void btnSelect_Click(object sender, EventArgs e){//定義了一個變量，來表示連接數據庫的字符串;string str = "server=.;database=mydb;uid=asp;pwd=asp";SqlConnection conn = new SqlConnection(str);conn.Open();string sql = "select * from student";//命令對象;SqlCommand cmd = new SqlCommand(sql, conn);//查詢,查詢完畢之后要存放到某個地方;數據集對象，包含若干 數據表對象;SqlDataAdapter sda = new SqlDataAdapter();sda.SelectCommand = cmd;DataSet ds = new DataSet();sda.Fill(ds, "student");DataTable dt=ds.Tables[0]; //獲取第一個數據表對象//這時候就填充過去了;//查看一下列名;for (int i = 0; i < dt.Columns.Count; i++) {Response.Write(dt.Columns[i].ColumnName+" ");}Response.Write("<br/>");//最終想要的是數據for (int i = 0; i < dt.Rows.Count; i++) {//老的方式，參考教材;//最新方式StringBuilder sb = new StringBuilder();sb.Append(dt.Rows[i]["stuId"].ToString()+" ");sb.Append(dt.Rows[i]["stuName"].ToString() + " ");sb.Append(dt.Rows[i]["age"].ToString() + " ");sb.Append(dt.Rows[i]["gender"].ToString() + " ");sb.Append(dt.Rows[i]["deptId"].ToString() + "<br/>");Response.Write(sb.ToString());}//關閉conn.Close();}} } 創作挑戰賽新人創作獎勵來咯，堅持創作打卡瓜分現金大獎

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