黑马程序员 连接字符串放到配置文件中
<?xml version="1.0" encoding="utf-8" ?> <configuration> <connectionStrings> <add name="dbConnStr" connectionString="Data Source=.; Initial Catalog=MyTest;User ID=sa;Password=123456"/> </connectionStrings> </configuration>
1 string connStr = ConfigurationManager.ConnectionStrings["dbConnStr"].ConnectionString; 2 //项目根目录添加一个“应用程序配置文件”,名字App.config 3 //App.config加节点,给add起一个name 4 //项目添加对System.configuration的引用(理解为添加开发包。System.Data就是ADO.Net的开发包) 5 //就能使用System.configuration里的ConfigurationManager类 6 //asp.net里只是Web.config 7 8 //MessageBox.Show(connStr); 9 DataSet dataset = new DataSet(); 10 using (SqlConnection conn = new SqlConnection(connStr)) 11 { 12 conn.Open(); 13 using (SqlCommand cmd = conn.CreateCommand()) 14 { 15 cmd.CommandText = "select * from T_Student where Age<@aaa"; 16 cmd.Parameters.Add(new SqlParameter("@aaa", 60)); 17 //cmd.ExecuteReader( 18 19 //SqlDataAdapter是一个帮我们把SqlCommand查询结果填充到DataSet 20 //中的类 21 SqlDataAdapter adapter = new SqlDataAdapter(cmd); 22 23 //DataSet相当于本地的一个复杂集合(List<int>) 24 25 adapter.Fill(dataset);//执行cmd并且把SqlCommand查询结果填充到DataSet 26 } 27 } 28 DataTable table = dataset.Tables[0]; 29 DataRowCollection rows = table.Rows; 30 for (int i = 0; i < rows.Count; i++) 31 { 32 DataRow row = rows[i]; 33 int age = (int)row["Age"]; 34 string name = (string)row["Name"]; 35 MessageBox.Show(name + "," + age); 36 } 37