In SQL, the use of left join (left Outer Join) and inner join is the opposite of right join (right Outer Join.

The following is a 137-row SQL statement. If you understand this, I want to know about left join and inner join. (My personal opinion only)

The following is a piece of code:

Select num1, num2, num3, num4, num5, num6, num7, num8, num9, num10, area. areacode, area. areaname, num11

From
(Select area_code areacode, area_name areaname, Fa. grade_path grade, Fa. ID
From fk_area fa
Where fa. father_id = (select ID from fk_area where area_code = 330203008000) and fa. is_deleted = 0) Area

Left join
(Select MC. zfjcs num1, MC. area_id areaid
From jd_mbkh_config MC
Where MC. is_deleted = 0
And MC. Year = '000000') map1 on map1.areaid = area. ID
 
Left join
(Select count (SC. ID) num2, info. fouth_area as areacode
From jd_safe_check SC
Inner join jd_company C on C. ID = SC. par_id2
Inner join fk_user_info info on info. ID = SC. user_id
Where SC. is_deleted = 0
And SC. father_id is null
And C. is_deleted = 0
And C. is_recycle = 0
And SC. check_time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And SC. check_time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss ')
Group by info. fouth_area) MAP2 on map2.areacode = area. areacode

Left join
(Select count (sc2.id) num3, info. fouth_area as areacode from jd_safe_check SC2 inner join jd_company C on C. ID = sc2.par _ Id2
Inner join fk_user_info info on info. ID = sc2.user _ id
Where sc2.is _ deleted = 0
And sc2.father _ id is not null
And C. is_deleted = 0
And C. is_recycle = 0
And sc2.check _ time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And sc2.check _ time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss ')
Group by info. fouth_area) map3 on map3.areacode = area. areacode

Left join
(Select count (sc3.id) num4, info. fouth_area as areacode from jd_safe_check SC3
Inner join jd_company C on C. ID = sc3.par _ Id2
Inner join fk_user_info info on info. ID = sc3.user _ id
Where not exists
(Select 1 from jd_hidden_trouble HT where sc3.id = HT. par_id2)
And sc3.is _ deleted = 0
And sc3.father _ id is null
And C. is_deleted = 0
And C. is_recycle = 0
And sc3.check _ time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And sc3.check _ time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss ')
Group by info. fouth_area) map4 on map4.areacode = area. areacode

Left join
(Select count (HT. ID) num5, info. fouth_area as areacode from jd_hidden_trouble HT
Inner join fk_user_info info on info. ID = Ht. user_id
Inner join jd_safe_check Che on che. ID = Ht. par_id2
Inner join jd_company C on C. ID = Ht. par_id
Where Ht. is_deleted = 0
And Ht. government_time is not null
And (HT. trouble_type = 'trouble _ type_common'
And C. is_deleted = 0 and C. is_recycle = 0
And Che. check_time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And Che. check_time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss '))
Group by info. fouth_area) map5 on map5.areacode = area. areacode

Left join
(Select count (ht2.id) num6, info. fouth_area as areacode from jd_hidden_trouble ht2
Inner join fk_user_info info on info. ID = ht2.user _ id
Inner join jd_safe_check Che on che. ID = ht2.par _ Id2
Inner join jd_company C on C. ID = ht2.par _ id
Where ht2.is _ deleted = 0
And ht2.government _ time is null
And (ht2.trouble _ type = 'trouble _ type_common'
And C. is_deleted = 0 and C. is_recycle = 0
And Che. check_time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And Che. check_time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss '))
Group by info. fouth_area) map6 on map6.areacode = area. areacode

Left join
(Select count (HT. ID) num7, info. fouth_area as areacode from jd_hidden_trouble HT
Inner join fk_user_info info on info. ID = Ht. user_id
Inner join jd_safe_check Che on che. ID = Ht. par_id2
Inner join jd_company C on C. ID = Ht. par_id
Where Ht. is_deleted = 0
And Ht. government_time is not null
And (HT. trouble_type = 'trouble _ type_great'
And C. is_deleted = 0 and C. is_recycle = 0
And Che. check_time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And Che. check_time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss '))
Group by info. fouth_area) map7 on map7.areacode = area. areacode

Left join
(Select count (ht2.id) num8, info. fouth_area as areacode from jd_hidden_trouble ht2
Inner join fk_user_info info on info. ID = ht2.user _ id
Inner join jd_safe_check Che on che. ID = ht2.par _ Id2
Inner join jd_company C on C. ID = ht2.par _ id
Where ht2.is _ deleted = 0
And ht2.government _ time is null
And (ht2.trouble _ type = 'trouble _ type_great'
And C. is_deleted = 0 and C. is_recycle = 0
And Che. check_time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And Che. check_time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss '))
Group by info. fouth_area) map8 on map8.areacode = area. areacode

Left join
(Select count (HT. ID) num9, info. fouth_area as areacode from jd_hidden_trouble HT
Inner join fk_user_info info on info. ID = Ht. user_id
Inner join jd_safe_check Che on che. ID = Ht. par_id2
Inner join jd_company C on C. ID = Ht. par_id
Where Ht. is_deleted = 0
And Ht. government_time is not null
And (HT. trouble_type = 'trouble _ type_other'
And C. is_deleted = 0 and C. is_recycle = 0
And Che. check_time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And Che. check_time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss '))
Group by info. fouth_area) map9 on map9.areacode = area. areacode

Left join
(Select count (ht2.id) num10, info. fouth_area as areacode from jd_hidden_trouble ht2
Inner join fk_user_info info on info. ID = ht2.user _ id
Inner join jd_safe_check Che on che. ID = ht2.par _ Id2
Inner join jd_company C on C. ID = ht2.par _ id
Where ht2.is _ deleted = 0
And ht2.government _ time is null
And (ht2.trouble _ type = 'trouble _ type_other'
And C. is_deleted = 0 and C. is_recycle = 0
And Che. check_time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And Che. check_time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss '))
Group by info. fouth_area) map10 on map10.areacode = area. areacode

Left join
(Select count (C. ID) num11, fouth_area as areacode from jd_company C
Where C. is_deleted = 0
And C. is_recycle = 0
And C. create_time> = to_date ('2017-01-01 00:00:00 ', 'yyyy-mm-dd hh24: MI: ss ')
And C. create_time <= to_date ('2017-12-31 23:59:59 ', 'yyyy-mm-dd hh24: MI: ss ')
Group by C. fouth_area) map11 on map11.areacode = area. areacode
Order by grade