Question

在SQL Server中，我有这个查询：

SELECT cvs.* 
  FROM dbo.ClientVoiceSetup cvs
 WHERE cvs.EnrollmentCode = 74311
/** Apply Vendor Data Scope **/
   AND cvs.ClientID IN (
SELECT DISTINCT cc.client_id
  FROM cli_case cc
 INNER JOIN cli_case_plan     ccp ON  cc.case_id         = ccp.case_id
 INNER JOIN service_plan       sp ON ccp.service_plan_id =  sp.service_plan_id
 INNER JOIN VendorServicePlan vsp ON  sp.service_plan_id = vsp.ServicePlanID
/** Apply Vendor ID from login **/
 WHERE vsp.VendorID = 4)

注意：在SQL中，客户端＆lt; - ＆gt; cli_case＆lt; - ＆gt; cli_case_plan没有定义任何FK。 service_plan＆lt; - ＆gt; VendorServicePlan＆lt; - ＆gt;供应商 do 定义了FK，其中VendorServicePlan仅为多对多连接表。

子查询是一个数据范围过滤器，将应用于多个不同的调用。当我将DB拖入EF时，我的结构略有不同。我有以下实体：

客户端 cli_case cli_case_plan service_plan（带有供应商ICollection）供应商（带有service_plan ICollection）

我在代码中创建了以下JOIN：

var q = (from cc in context.cli_case
    join ccp in context.cli_case_plan on cc.case_id equals ccp.case_id
    join sp in context.service_plan on ccp.service_plan_id equals sp.service_plan_id
    select cc.client_id);
return q.ToList();

我在如何添加＆＃34; WHERE子句＆＃34; for VendorID == myInput。

作为旁注：我想知道如何返回非物质化EF语句而不是DB调用的结果。长期的想法是将此声明作为过滤器注入到正常的＆＃34; EF调用所以当它实现时它包括过滤。（为什么在可以调用一次时调用数据库两次？）除非有更好的方法？

Answer 1

想出来。

LINQ for SQL

var p = (from cc in context.cli_case
         join ccp in context.cli_case_plan on cc.case_id equals ccp.case_id
         join sp in context.service_plan on ccp.service_plan_id equals sp.service_plan_id
         where sp.Vendors.Any(a => a.VendorID == vendorId)
         select cc.client_id);

LINQ for Objects

    var q = context.cli_case.Join(context.cli_case_plan, cc => cc.case_id, ccp => ccp.case_id, (cc, ccp) => new {cc, ccp})
        .Join(context.service_plan, @t => @t.ccp.service_plan_id, sp => sp.service_plan_id, (@t, sp) => new {@t, sp})
        .Where(ven => ven.sp.Vendors.Any(a => a.VendorID == vendorId))
        .Select(a => a.@t.cc.client_id);

然后我可以将其作为IQuerayble＆lt; int＆gt;并进一步使用它：

var enrollmentCode = 13524;
// provides the underlying SQL, does not hit the DB...
var clientList = db.GetClientIdListFromVendorId(4);
// set WHERE clause to filter on enrollmentCode and allowed client list...
var q = db.ClientSetups
          .Where(a => a.EnrollmentCode == enrollmentCode
                   && clientList.Contains(a.ClientID))
          .ToList();

EF中的多表连接

1 个答案: