仅检索单个值 [英] Retrieve a single value only

问题描述

如果要从数据库检索某些值，则必须始终使用应包含大量数据的类.

就我而言，我只想从存储过程中检索一个值，我真的需要使用只包含单个值的类吗?
当我不想使用类时，应该如何在.hbm.xml内部创建以及如何用C#代码编写?

它不是IList< string>或类似.仅单个值是int字符串.

当需要具有包含大量数据的类时，将使用下面的代码.


sp_retrieveAllProductList.hbm.xml

If you want to retrieve some value from a database you always has to use a class that shall contain a lot of data.

In my case, I want to retrieve one value only from a stored procedure and do I really need to use a class that shall contain a single value only?
How should I create inside of the .hbm.xml and how should I write in c# code when I dont want to use a class?

It is not a IList<string> or similiar. A single value only that is int string.

The code below is used when you need to have class that shall contain a lot of data.


sp_retrieveAllProductList.hbm.xml

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="data_layer" namespace="data_layer">
  <sql-query name="sp_retrieveAllProductList">
    <return-scalar column="Produkt" type="string" />
    <return-scalar column="Produkt_kategori" type="string" />
    <return-scalar column="btn_namn" type="string" />
    exec sp_retrieveAllProductList :Produkt_kategori
  </sql-query>
</hibernate-mapping>

public IList<Product4> RetrieveAllProductWithPriceNameAndBtn()
    {
        return _session.GetNamedQuery("sp_retrieveAllProductList2")
                        .SetResultTransformer(Transformers.AliasToBean(typeof(Product4)))
                        .List<Product4>();
    }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace data_layer
{
    public class Product4
    {
        public virtual string PK_produkt { get; set; }
        public virtual string Produkt { get; set; }
        public virtual string Produkt_kostnad { get; set; }
        public virtual string btn_namn { get; set; }
    }
}

推荐答案

请参阅如何若要:创建并执行返回单个值的SQL语句 [ ^ ]，以获取有关如何执行返回单个值的SQL语句的信息.

See How to: Create and Execute an SQL Statement that Returns a Single Value[^] for information on how to execute an SQL statement that returns a single value.

如果要获取字符串列表，请尝试此操作

Try this if you want to get a list of string

IList<string> names = Session.CreateSQLQuery("EXEC sp_retrieveAllProductList2")			
			.List<string>();

如果要返回单个值

If you want to return a single value

Session
    .CreateSQLQuery(sql)
    .UniqueResult<string>();

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