跟我学 NHibernate （一）

NHibernate 是一个强大的 ORM　框架，本博文主要就 NHibernate 的使用方法及语法做一些简单的介绍。
 
 1.NHibernate 语法
 
  新建一个类，命名为： QueryCriteriaAPI， 并创建构造函数

        private ISession _session;

        public ISession Session

        {

            set

            {

                _session = value;

            }

        }

        public QueryCriteriaAPI(ISession session)

        {

            _session = session;

        }

    #region 语法学习

        /// <summary>

        /// 创建ICriteria实例

        /// </summary>

        /// <returns></returns>

        public IList<Customer> CreateCriteria()

        {

            //NHibernate.ICriteria这个接口代表对一个特定的持久化类的查询。

            //ISession是用来制造Criteria实例的工厂。

            var crit = _session.CreateCriteria(typeof(Customer));

            crit.SetMaxResults(50);

            var customers = crit.List<Customer>();

            return customers;

        }

        /// <summary>

        /// 缩小结果集范围

        /// </summary>

        /// <returns></returns>

        public IList<Customer> Narrowing()

        {

            //一个查询条件(Criterion)是NHibernate.ICriterion接口的一个实例。

            //类NHibernate.Expression.Expression定义了获得一些内置的ICriterion类型的工厂方法。

            var customers = _session.CreateCriteria(typeof(Customer))

                .Add(Restrictions.Like("Firstname", "YJing%"))

                .Add(Restrictions.Between("Lastname", "A%", "Y%"))

                .List<Customer>();

            //表达式（Expressions）可以按照逻辑分组

            //IList<Customer> customers = _session.CreateCriteria(typeof(Customer))

            //    .Add(Restrictions.Like("Firstname", "YJ%"))

            //    .Add(Restrictions.Or(

            //    Restrictions.Eq("Lastname", "L%"),

            //    Restrictions.IsNull("Lastname")

            //    ))

            //    .List<Customer>();

            //IList<Customer> customers = _session.CreateCriteria(typeof(Customer))

            //    .Add(Restrictions.In("Firstname", new string[] { "YJing", "YJingLee", "Y" }))

            //    .Add(Restrictions.Disjunction()

            //    .Add(Restrictions.IsNull("Lastname"))

            //    .Add(Restrictions.Eq("Lastname", "Lee"))

            //    .Add(Restrictions.Eq("Lastname", "xyz"))

            //    ).List<Customer>();

            //预制的条件类型（Expression的子类）。可以直接嵌入SQL。

            //{alias}是一个占位符，它将会被所查询实体的行别名所替代

            //Parameter paramName = new Parameter("someName", new StringSqlType());

            //IList<Customer> customers = _session.CreateCriteria(typeof(Customer))

            //    .Add(Expression.Sql(

            //      new SqlString(new object[]{

            //          "lower({alias}.Lastname) like lower(","Lastname",")"}), "YJing%", NHibernateUtil.String))

            //          .List<Customer>();

            return customers;

        }

        /// <summary>

        /// 排序Order by

        /// </summary>

        /// <returns></returns>

        public IList<Customer> Order()

        {

            //使用ICriteria.Order对结果集排序,true=asc,false=desc

            return _session.CreateCriteria(typeof(Customer))

                .Add(Restrictions.Like("Firstname", "Y%"))

                .AddOrder(new NHibernate.Criterion.Order("Lastname", true))

                .AddOrder(new NHibernate.Criterion.Order("Firstname", false))

                .List<Customer>();

        }

        #endregion

2. 实例学习

        #region 实例学习

        /// <summary>

        /// 利用CriteriaAPI按Firstname查询顾客

        /// </summary>

        /// <param name="firstname"></param>

        /// <returns>顾客列表</returns>

        public IList<Customer> UseCriteriaAPI_GetCustomersByFirstname(string firstname)

        {

            //NHibernate1.2写法

            //return _session.CreateCriteria(typeof(Customer))

            //    .Add(new NHibernate.Expression.EqExpression("Firstname", firstname))

            //    .List<Customer>();

            //NHibernate2.0写法

            //return _session.CreateCriteria(typeof(Customer))

            //    .Add(Expression.Eq("Firstname", firstname))

            //    .List<Customer>();

            //使用Name封装：.Add(Restrictions.Eq("Name.Firstname", firstname))

            return _session.CreateCriteria(typeof(Customer))

                .Add(Restrictions.Eq("Firstname", firstname))

                .List<Customer>();

        }

        /// <summary>

        /// 利用CriteriaAPI按Firstname和Lastname查询顾客

        /// </summary>

        /// <param name="firstname"></param>

        /// <param name="lastname"></param>

        /// <returns></returns>

        public IList<Customer> UseCriteriaAPI_GetCustomersByFirstnameAndLastname(string firstname, string lastname)

        {

            //NHibernate1.2写法

            //return _session.CreateCriteria(typeof(Customer))

            //    .Add(new NHibernate.Expression.EqExpression("Firstname", firstname))

            //    .Add(new NHibernate.Expression.EqExpression("Lastname", lastname))

            //    .List<Customer>();

            //NHibernate2.0写法

            //使用Name封装：.Add(Restrictions.Eq("Firstname", firstname))

            return _session.CreateCriteria(typeof(Customer))

                .Add(Restrictions.Eq("Firstname", firstname))

                .Add(Restrictions.Eq("Lastname", lastname))

                .List<Customer>();

        }

        /// <summary>

        /// 利用CriteriaAPI获取顾客ID大于CustomerId的顾客

        /// </summary>

        /// <param name="customerId">顾客ID</param>

        /// <returns>顾客列表</returns>

        public IList<Customer> UseCriteriaAPI_GetCutomersWithIdGreaterThan(int customerId)

        {

            //NHibernate1.2写法

            //return _session.CreateCriteria(typeof(Customer))

            //    .Add(new NHibernate.Expression.GtExpression("CustomerId", customerId))

            //    .List<Customer>();

            //NHibernate2.0写法

            return _session.CreateCriteria(typeof(Customer))

                .Add(Restrictions.Gt("CustomerId", customerId))

                .List<Customer>();

        }

        #endregion

由于时间的仓促，这里粘贴了主要的代码片段