zoukankan      html  css  js  c++  java
  • 不要轻易使用linq代替sql

    使用Entityframework+Reposity模式 写出的代码执行效率极低。

    Linq代码:

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

    转化的SQL语句:

    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 )

    linq转出来的语句在数据库上执行,花费40多秒:

    Total query runtime: 40.1 secs
    检索到 100127 行。

    实现同样的业务,自己写的sql语句:

    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

    执行自己写的sql,花费不到1秒:

    Total query runtime: 680 msec
    检索到 2 行。
  • 相关阅读:
    【npm】mac下node环境搭建
    pair求解迷宫的最短路径(bfs)
    dos窗口启动关闭Mysql
    二维差分模板
    一维差分模板
    DOS命令
    迷宫搜索dfs实现
    DFS 迷宫问题
    BFS广搜解决迷宫问题(跟着B站大佬手撸)
    蓝桥杯省赛模拟赛
  • 原文地址:https://www.cnblogs.com/Fly-sky/p/5436036.html
Copyright © 2011-2022 走看看