Question

你能帮我在linq中生成这个sql查询吗？

   SELECT DATA_MAX_qh.DATA_MAX,DATA_MAX_qh.[QUOT_CODE],[QUOT_VALUE],q.QUOT_DESCR,q.QUOT_DESCR_ALIAS
            FROM [dbo].[QUOTATION_HISTORY] qh INNER JOIN
            (SELECT MAX(QUOT_DATA) DATA_MAX, QUOT_CODE
            FROM [dbo].[QUOTATION_HISTORY]
            GROUP BY [QUOT_CODE]) DATA_MAX_qh on
            DATA_MAX_qh.DATA_MAX = qh.QUOT_DATA and  DATA_MAX_qh.QUOT_CODE = qh.QUOT_CODE
            inner join [dbo].[AN_QUOTAZIONE] q on q.QUOT_CODE = qh.QUOT_CODE

我需要的第一件事是在表格上分组以获得最大日期及其匹配值然后使用此过滤表进行更完整的选择

我已经开始使用

了

  var qhmaxdatevalue = from qh in context.QUOTATION_HISTORY
                                 where qh.QUOT_DATA < System.DateTime.Now
                                 group qh by qh.QUOT_CODE into qhgroupedbycode
                                 select new { Quot_Code = qhgroupedbycode.Key, Data_Max = qhgroupedbycode.Max(x => x.QUOT_DATA) };

但现在我该怎么办？使用嵌套查询？

你能帮助我吗？

Answer 1

var query = 
context.QUOTATION_HISTORY
.GroupBy            
(
    x=>x.QUOT_CODE
)
.Select
(
    x=>
    new 
    {
        QUOT_CODE = x.Key,
        DATA_MAX = x.Max(z=>z.QUOT_DATA)
    }
)
.Join
(
    context.QUOTATION_HISTORY,
    x=>new{DATA_MAX,QUOT_CODE},
    x=>new{QUOT_DATA,QUOT_CODE},
    (DATA_MAX_qh,qh)=>new
    {
        DATA_MAX_qh.DATA_MAX,
        DATA_MAX_qh.QUOT_CODE,
        qh.QUOT_VALUE
    }
)
.Join
(
    context.AN_QUOTAZIONE,
    x=>QUOT_CODE,
    x=>QUOT_CODE,
    (qh,q)=>new
    {
        qh.DATA_MAX,
        qh.QUOT_CODE,
        qh.QUOT_VALUE,
        q.QUOT_DESCR,
        q.QUOT_DESCR_ALIAS
    }
);

Answer 2

也许是这样的：

var result= (
        from qh in db.QUOTATION_HISTORY
        from DATA_MAX_qh in 
            (
                from innerqh in db.QUOTATION_HISTORY
                group innerqh by innerqh.QUOT_CODE into g
                select new
                {
                    DATA_MAX=g.Max(x => x.QUOT_DATA),
                    QUOT_CODE=g.Key
                }
            ).Where(a=>a.DATA_MAX == qh.QUOT_DATA && a.QUOT_CODE == qh.QUOT_CODE)
        join q in db.AN_QUOTAZIONE 
            on qh.QUOT_CODE equals q.QUOT_CODE
        select new 
        {
            DATA_MAX_qh.DATA_MAX,
            DATA_MAX_qh.QUOT_CODE,
            qh.QUOT_VALUE,
            q.QUOT_DESCR,
            q.QUOT_DESCR_ALIAS
        }
    ).ToList();

其中db是linq数据上下文

嵌套查询linq到实体

2 个答案: