C# 用linq方法语法连接两个表,MVC EntityFramework
我正在使用两个表:CI_CLIENTRISK(SCD类型2)。。。和QB_发票_标题() 它们可以通过ClientID连接。我想从本质上复制此查询:C# 用linq方法语法连接两个表,MVC EntityFramework,c#,sql,asp.net-mvc,entity-framework,linq,C#,Sql,Asp.net Mvc,Entity Framework,Linq,我正在使用两个表:CI_CLIENTRISK(SCD类型2)。。。和QB_发票_标题() 它们可以通过ClientID连接。我想从本质上复制此查询: SELECT a.ClientID, MAX(b.InvoiceDt) AS MaxInvoiceDt (omitted for brevity) FROM CI_CLIENTRISKADJS a INNER JOIN QB_INVOICES_HEADER b ON a.ClientID = b.ClientID WHERE a.I
SELECT a.ClientID,
MAX(b.InvoiceDt) AS MaxInvoiceDt
(omitted for brevity)
FROM CI_CLIENTRISKADJS a
INNER JOIN QB_INVOICES_HEADER b
ON a.ClientID = b.ClientID
WHERE a.IsActive = 1
GROUP BY a.ClientID
ORDER BY MaxInvoiceDt DESC
这是我到目前为止所拥有的。它不会返回任何记录
using (var db = new PLOGITENS01Entities())
{
var rvClientRiskAdjs = db.CI_CLIENTRISKADJS
.Take(50)
.Join(db.QB_INVOICES_HEADER,
a => a.ClientID,
b => b.ClientID,
(a, b) => new { Risk = a, Invoices = b })
.Where(a => a.Risk.IsActive == 1)
.OrderByDescending(o => o.Invoices.InvoiceDt)
.Select(c => new ClientRiskModel()
{
ClientRiskId = c.Risk.ClientRiskID,
ClientName = c.Risk.CI_CLIENTLIST.ClientName,
ClientId = c.Risk.ClientID,
ClientRiskAdjs = c.Risk.ClientRiskAdjs,
RecordValidStartDt = c.Risk.RecordValidStartDt,
RecordValidEnddt = c.Risk.RecordValidEnddt,
IsActive = c.Risk.IsActive
})
.ToList();
return View(new GridModel(rvClientRiskAdjs));
}
试着把你的
.Take(50)
方法放在你最后的之后。选择和之前。ToList()
。实际上,您只需要获取第一个表的前50条记录,然后从那里加入。我假设在第一个表的前50条记录中没有与第二个表的连接;因此,您的结果将有0条记录。我在阅读本文时偶然发现了这个解决方案:
谢谢你的提示。:)这是可行的,但它没有考虑最大聚合(在SQL查询的第二行中找到)。它返回所有客户端ID的列表,不返回任何组。我最终通过这篇文章找到了答案:
var rvClientRiskAdjs = (from ri in db.CI_CLIENTRISKADJS
join qb in
(from qb in db.QB_INVOICES_HEADER
orderby qb.InvoiceDt ascending
group qb by qb.ClientID into grp
select new
{
InvoiceDt = grp.Max(s => s.InvoiceDt),
ClientID = grp.Key
})
on ri.ClientID equals qb.ClientID
orderby qb.InvoiceDt descending
where ri.IsActive == 1
select new ClientRiskModel()
{
ClientRiskId = ri.ClientRiskID,
ClientName = ri.CI_CLIENTLIST.ClientName,
ClientId = ri.ClientID,
ClientRiskAdjs = ri.ClientRiskAdjs,
RecordValidEnddt = ri.RecordValidEnddt,
RecordValidStartDt = ri.RecordValidStartDt
})
.ToList();