Dapper.NET 使用简单举例

Dapper是.NET下一个micro的ORM，它和Entity Framework或Nhibnate不同，属于轻量级的，并且是半自动的。也就是说实体类都要自己写。它没有复杂的配置文件，一个单文件就可以了。

现在已经取代了原来的SqlHelper优点：

• Execute执行数据库脚本

        public static void OpeartData()
        {
            string sqlconnct = System.Configuration.ConfigurationManager.ConnectionStrings["myconnect"].ConnectionString;
            using (IDbConnection comm = new SqlConnection(sqlconnct))
            {
                comm.Open();
                //Book book = new Book() { Name="C#9论述",Id=1 };
                string query = "insert into Book(Name) values(@name)";
                //添加，可以执行SQL脚本

                //comm.Execute(query, book);
                //comm.Execute(query, new { name = "Java Learn" });


                query = "UPDATE Book SET  Name=@name WHERE BookId =@id";
                //comm.Execute(query, book);
                //comm.Execute(query, new {name="C985426",BookId=1 });

                query = "DELETE FROM Book WHERE BookId = @id";
                //var idsult=comm.Execute(query, new { name = "C985426", BookId = 1 });

                query = "select * from Book where BookId=@id";
                //var ruslt = comm.Query<Book>(query).ToList();
                // var ruslt = comm.Query<Book>(query, new { BookId = 2 }).FirstOrDefault();
            }
        }

• Query执行数据库脚本查询

  • One To More 查询

  public static Book OpeartMoData()
          {
              string sqlconnct = System.Configuration.ConfigurationManager.ConnectionStrings["myconnect"].ConnectionString;
              using (IDbConnection conn = new SqlConnection(sqlconnct))
              {
                  conn.Open();
                  string query = "SELECT * FROM Book b LEFT JOIN BookReview br ON br.BookId = b.Id WHERE b.id = @id";
                  Book lookup = null;
                  //Query<TFirst, TSecond, TReturn>
                  var b = conn.Query<Book, BookReview, Book>(query,
                   (book, bookReview) =>
                   {
                       //扫描第一条记录，判断非空和非重复
                       if (lookup == null || lookup.BookId != book.BookId)
                           lookup = book;
                       //书对应的书评非空，加入当前书的书评List中，最后把重复的书去掉。
                       if (bookReview != null)
                           lookup.Reviews.Add(bookReview);
                       return lookup;
                   }, new { id = 2 }, splitOn: "id").Distinct().SingleOrDefault();
                  return b;
              }
          }

  • One To One 查询

   public static BookReview OpeartData1T1()
          {
              string sqlconnct = System.Configuration.ConfigurationManager.ConnectionStrings["myconnect"].ConnectionString;
              using (IDbConnection conn = new SqlConnection(sqlconnct))
              {
                  BookReview br;
                  string query = "SELECT br.Id,b.BookId,Content,Name FROM BookReview br  inner JOIN Book b ON br.BookId = b.BookId  WHERE br.id = @id";
                  using (conn)
                  {
                      br = conn.Query<BookReview, Book, BookReview>(query,
                     (bookReview, book) =>
                     {
                         bookReview.AssoicationWithBook = book;
                         return bookReview;
                     }, new { id = 4 }, splitOn: "BookId",commandType:CommandType.StoredProcedure).FirstOrDefault();
                      return br;
                  }
              }
          }

  • 执行事务

   public static void BookTransaction()
          {
              string sqlconnct = System.Configuration.ConfigurationManager.ConnectionStrings["myconnect"].ConnectionString;
              using (IDbConnection conn = new SqlConnection(sqlconnct))
              {
                  conn.Open();
                  //开始事务
                  IDbTransaction transaction = conn.BeginTransaction();
                  try
                  {
                      string query = "DELETE FROM Book WHERE id = @id";
                      string query2 = "DELETE FROM BookReview WHERE BookId = @BookId";
                      conn.Execute(query2, new { BookId = 2 }, transaction, null, null);
                      conn.Execute(query, new { id = 2 }, transaction, null, null);
                      //提交事务
                      transaction.Commit();
                  }
                  catch (Exception ex)
                  {
                      //出现异常，事务Rollback
                      transaction.Rollback();
                      throw new Exception(ex.Message);
                  }
              }
          }