oralce SQL执行对比

要查询一个人的身高、体重为数字，而体重指数为空的数据。

类似的查询，可能会很多，例如：

userInfo表结构为：

id	user_id	name	code	val
1	35	王五	age	22
2	35	王五	mobile	18612341234
3	35	王五	idno	331228198501024423
-	-	-	-	-
4	37	王六	age	19
5	37	王六	mobile	13212341234
6	37	王六	idno	null
-	-	-	-	-
8	39	王七	age	18
9	39	王七	mobile	18612341234
10	39	王七	idno	13312341234

查询
    年龄>18
    手机号不为空
    哪些人没填写身份证号

正确的查询结果是“王六”

三条语句，完成同样的查询功能，执行效率对比
表结构

第一种写法，使用exists进行查询

 select count(*)
   from pis_checkitemindexresult c
  where 
    exists (select 1
           from pis_checkitemindexresult c2
          where c2.itemindexmiscode = '1.2.4.1' --身高
            and f_is_num(c2.itemindexresultvalue) = 'T'
            and c2.workno = c.workno)
    and exists (select 1
           from pis_checkitemindexresult c3
          where c3.itemindexmiscode = '1.2.4.2' --体重
            and f_is_num(c3.itemindexresultvalue) = 'T'
            and c3.workno = c.workno)
    and c.itemindexmiscode = '1.2.4.3' --体重指数
    and c.itemindexresultvalue is null

PLSQL执行计划：

第二种写法，使用count(*)来查询

select count(*)
   from pis_checkitemindexresult c
  where
  (select count(*)
     from pis_checkitemindexresult c2
    where c2.itemindexmiscode = '1.2.4.1' --身高
      and f_is_num(c2.itemindexresultvalue) = 'T'
      and c2.workno = c.workno) > 0
      
  and (select count(*)
     from pis_checkitemindexresult c3
    where c3.itemindexmiscode = '1.2.4.2' --体重
      and f_is_num(c3.itemindexresultvalue) = 'T'
      and c3.workno = c.workno) > 0
 
  and c.itemindexmiscode = '1.2.4.3' --体重指数
  and c.itemindexresultvalue is null

PLSQL执行计划：

第三种写法：使用inner join来关联查询

select count(*)
  from pis_checkitemindexresult c
  inner join pis_checkitemindexresult c2 on c.workno = c2.workno
  inner join pis_checkitemindexresult c3 on c.workno = c3.workno
 where
   
   c2.itemindexmiscode = '1.2.4.1'
   and f_is_num(c2.itemindexresultvalue)='T'
   

   and c3.itemindexmiscode = '1.2.4.2'
   and f_is_num(c3.itemindexresultvalue)='T'
   

   and c.itemindexmiscode = '1.2.4.3'
   and c.itemindexresultvalue is null

PLSQL执行计划：

问题是哪种方法执行效率最高，现在每个都10分钟都执行不完。

猜你喜欢