不要轻易使用linq代替sql

 var querySql = rel_project_personservice.GetItems(r => r.Person).Where(w => w.ProjectId == projectId && w.Person.College.University.Province == provinceName);

SELECT "Extent1"."personid", "Extent1"."projectid", "Extent1"."isallotroom", "Extent1"."randomcode", "Extent1"."admissionticket", 
"Extent1"."pushstatus", "Extent1"."createdtime", "Extent1"."examinationroomid", "Extent2"."id", "Extent2"."name", "Extent2"."idnumber",
 "Extent2"."gender", "Extent2"."mobile", "Extent2"."idcard", "Extent2"."email", "Extent2"."degree", "Extent2"."nation", "Extent2"."major", 
"Extent2"."graduatedate", "Extent2"."livingcity", "Extent2"."accountlocation", "Extent2"."expectcity", "Extent2"."enterprisenature", 
"Extent2"."expectindustry", "Extent2"."expectjob", "Extent2"."collegeid", "Extent2"."status", "Extent2"."signuptype", 
"Extent2"."createdtime" AS "createdtime1", "Extent2"."modifiedtime", "Extent2"."createdby", "Extent2"."modifiedby", 
"Extent2"."classname", "Extent2"."idcardtype", "Extent2"."birthday", "Extent2"."xzid", "Extent2"."szid", "Extent2"."testcity", 
"Extent2"."graduateschool", "Extent2"."degreeid", "Extent2"."nationid", "Extent2"."majorid", "Extent2"."accountlocationid", 
"Extent2"."livingcityid", "Extent2"."expectcityid", "Extent2"."enterprisenatureid", "Extent2"."expectindustryid", 
"Extent2"."expectjobid", "Extent2"."testcityid" FROM "public"."rel_project_person" AS "Extent1" INNER JOIN "public"."person" AS "Extent2" 
ON "Extent1"."personid" = "Extent2"."id" LEFT OUTER JOIN "public"."college" AS "Extent3" ON "Extent2"."collegeid" = "Extent3"."id"
 LEFT OUTER JOIN "public"."university" AS "Extent4" ON "Extent3"."universityid" = "Extent4"."id" 
 WHERE "Extent1"."projectid" = 11 AND ("Extent4"."province" = ‘北京‘ OR "Extent4"."province" IS NULL )

Total query runtime: 40.1 secs
检索到 100127 行。

Select C.UNIVERSITYID,c.name,count(p.id)
from Person p
join Rel_Project_Person R on P.id =R.PersonID
join College C on p.CollegeID = C.id
where R.ProjectId =11 and C.universityid IN
(
Select id from University where Province = ‘北京‘
)
group by C.UNIVERSITYID,c.name

Total query runtime: 680 msec
检索到 2 行。