ADO.NET中的模型及对象

 ???????????//连接字符串 ???????????string conStr = @"server=.;database=MyDataBase;uid=sa;pwd=sa"; ???????????//要执行的sql语句 ???????????string sql = "insert into MyDataBase(Id,Name,Age,Sex) values(1,‘曹操‘,500,‘m‘)"; ???????????//创建连接对象 ???????????using (SqlConnection conn = new SqlConnection(conStr)) ???????????{ ???????????????//第一种写法； ???????????????//创建执行对象（执行sql语句） ???????????????//using (SqlCommand cmd = new SqlCommand()) ???????????????//{ ???????????????// ???cmd.Connection = conn; ???????????????// ???cmd.CommandText = sql; ???????????????// ???//打开数据库 ???????????????// ???conn.Open(); ???????????????// ???//返回收影响的行数 ???????????????// ???int count = cmd.ExecuteNonQuery(); ???????????????// ???Console.WriteLine("{0}行收影响", count); ???????????????//} ???????????????//第二种写法 ?在构造函数中传入SQL语句和连接对象 ???????????????using (SqlCommand cmd = new SqlCommand(sql, conn)) ???????????????{ ???????????????????conn.Open(); ???????????????????int count = cmd.ExecuteNonQuery(); ???????????????????Console.WriteLine("{0}行受影响", count); ???????????????} ???????????} ???????????Console.ReadKey()

 ???????????// 提示用户输入用户名 ???????????Console.Write("Enter User Id:"); ???????????string userName = Console.ReadLine(); ???????????// 提示用户输入密码 ???????????Console.Write("Enter Password:"); ???????????string userPwd = Console.ReadLine(); ???????????//连接字符串 ???????????string conStr = @"server=.;databae=MyDataBase;uid=sa;pwd=sa"; ???????????//sql 语句 ???????????string sql = string.Format("select count(*) from Users where userName=‘{0}‘ and userPwd={1}", userName, userPwd); ???????????int count = 0; ???????????using (SqlConnection conn = new SqlConnection(conStr)) ???????????{ ???????????????using (SqlCommand cmd = new SqlCommand(sql, conn)) ???????????????{ ???????????????????conn.Open(); ???????????????????//返回首行首列是Object类型 ???????????????????count = (int)cmd.ExecuteScalar(); ???????????????} ???????????} ???????????if (count > 0) ???????????{ ???????????????Console.WriteLine("登录成功"); ???????????} ???????????else ???????????{ ???????????????Console.WriteLine("登录失败"); ???????????}

 ???????????//连接字符串 ???????????string conStr = @"server=.;database=MyDataBase;uid=sa;pwd=sa"; ???????????//sql语句 ?查询整张表的数据(逐行取) ???????????string sql = "select * from Data"; ???????????using (SqlConnection conn = new SqlConnection(conStr)) ???????????{ ???????????????using (SqlCommand cmd = new SqlCommand(sql, conn)) ???????????????{ ???????????????????conn.Open(); ???????????????????//一次一行数据来回读取数据 ???????????????????SqlDataReader reader = cmd.ExecuteReader(); ???????????????????using (reader)//每次向下读取一行 ?直到读取完为止 ???????????????????{ ???????????????????????Console.WriteLine("{0},{1},{2}", reader[0], reader[1], reader[2]); ???????????????????} ???????????????????while (reader.Read())//循环读取每一行数据 直到读取完为止 ???????????????????{ ???????????????????????List<string> list = new List<string>();//每读取一行 ?创建一行string类型 ???????????????????????for (int i = 0; i < reader.FieldCount; i++)//循环遍历每一行数据的每一列数据 ???????????????????????{ ???????????????????????????list.Add(reader[i].ToString()); ???????????????????????} ???????????????????????Console.WriteLine(string.Join(",", list)); ???????????????????} ???????????????} ???????????}

 　　　　　　 string conStr = @"server=.;database=MyDataBase;uid=sa;pwd=sa"; ???????????string sql = "select * top 10 from Data"; ???????????DataSet ds = new DataSet(); ???????????using (SqlDataAdapter adapter = new SqlDataAdapter(sql, conStr)) ???????????{ ???????????????adapter.Fill(ds); ???????????} ???????????//取出DataSet中的数据 ???????????//遍历取出DataSet ds中的每一个表 ???????????for (int i = 0; i < ds.Tables.Count; i++) ???????????{ ???????????????DataTable dt = ds.Tables[i]; ???????????????//遍历DataTable dt中的每一行 ???????????????for (int j = 0; j < dt.Rows.Count; j++) ???????????????{ ???????????????????DataRow row = dt.Rows[i]; ???????????????????List<string> list = new List<string>(); ???????????????????for (int k = 0; k < row.ItemArray.Length; k++) ???????????????????{ ???????????????????????list.Add(row.ItemArray[k].ToString()); ???????????????????} ???????????????????Console.WriteLine(string.Join(",",list)); ???????????????} ???????????}