ADO.NET封装代码

一、在App.config配置文件中，配置连接字符串

二、SqlHelper类，封装对数据库操作的代码

    class SqlHelper
    {
        //读取配置文件中的连接字符串
        private static string connStr = ConfigurationManager.ConnectionStrings["dbConnStr"].ConnectionString;

        public static int ExecuteNonQuery(string sql,params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    return cmd.ExecuteNonQuery();
                }
            }
        }

        public static object ExecuteScalar(string sql, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    return cmd.ExecuteScalar();
                }
            }
        }

        //只用来执行查询结果比较少的sql
        public static DataTable ExecuteDataTable(string sql, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);

                    SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                    DataSet dataset = new DataSet();
                    adapter.Fill(dataset);
                    return dataset.Tables[0];
                }
            }
        }
    }

三、测试代码

           SqlHelper.ExecuteNonQuery("insert into T_Student(Name,Age) values('a',33)");
           DataTable table = SqlHelper.ExecuteDataTable("select * from T_Student where Age=@Age or Name=@Name",
                new SqlParameter("@Age", 50),new SqlParameter("@Name","yzk"));
           foreach (DataRow row in table.Rows)
           {
               string name = (string)row["Name"];
               MessageBox.Show(name);
           }