用Entity Framework 连表查询

Posted 2023-03-19

参考技术A public List<Article> Select()

       

            var result = from article in le.Article select article;

            return result.ToList();

       

public Article SelectById(int id)

       

            var result = (from article in le.Article

                          where article.id == id select article).Single();

            return result;

       

public int Add(Article article)

       

            le.Article.Add(article);

            int count = le.SaveChanges();

            return count;

       

public int Remove(Article article)

       

            le.Article.Remove(article);

            int count = le.SaveChanges();

            return count;

       

public int Update(Article article)

       

            le.Entry<Article>(article).State = System.Data.Entity.EntityState.Modified;

            int count = le.SaveChanges();

            return count;

       

LunTanEntities le = new LunTanEntities();

        public List<Catelog> Select()

       

            //return le.Catelog.Select(p => p).ToList();

            var result = from catelog in le.Catelog select catelog;

            return result.ToList();

       

public int Add(Article article)

       

            return tanDAO.Add(article);

       

public List<Article> Select()

       

            return tanDAO.Select();

       

public Article SelectById(int id)

       

            return tanDAO.SelectById(id);

       

public List<Catelog> Select()

       

            return dAO.Select();

       

<div>

            <asp:HyperLink ID="HyperLink1" NavigateUrl="~/Add.aspx" runat="server">添加文章</asp:HyperLink>

            <asp:GridView ID="GridView1" runat="server" DataSourceID="ObjectDataSource1"></asp:GridView>

            <asp:ObjectDataSource ID="ObjectDataSource1" runat="server" SelectMethod="GetSelect" TypeName="BLL.ArCaService"></asp:ObjectDataSource>

        </div>

csharp 使用Entity Framework和OracleParameters执行查询

public async Task<bool> IsExist(string data1, string data2)
{
    var db = _dbContextProvider.GetDbContext().Database;

    var parameters = new OracleParameter[2];
    var pParam1 = new OracleParameter(":param1", OracleDbType.Varchar2, 50) { Value = data1 };
    var pParam2 = new OracleParameter(":param2", OracleDbType.Varchar2, 50) { Value = data2 };

    string sql = @" select count(1)
                    from table1 p
                    where p.Column1 = :param1 and p.Column2 = :param2";

    return await db.SqlQuery<int>(sql, pParam2, pParam1).AnyAsync();
}

//Be careful on parameters order.