How do I update multiple rows in MySQL(AuroraDB)? - mysql

Question

Table Mapper
|-------------------------------------------|
| id | info_fk | reg_fk |
| 1 | 100 | |
| 2 | 101 | |
| 3 | 101 | |
| 4 | 102 | |
| 5 | 102 | |
| 6 | 103 | |
|-------------------------------------------|
Table Region
|---------------------------|
| id | region_id |
| 1 | A101 |
| 2 | A102 |
| 3 | A301 |
| 4 | B101 |
|---------------------------|
Table Info
|--------------------------------------|
| id | address |
| 100 | A101 |
| 101 | A102;A101 |
| 102 | A301;B101 |
| 103 | B101 |
|--------------------------------------|
I want to map info table's id and fill table Mapper. Above sample, my desired output is to make table Mapper to
Table Mapper
|-------------------------------------------|
| id | info_fk | reg_fk |
| 1 | 100 | 1 |
| 2 | 101 | 1 |
| 3 | 101 | 2 |
| 4 | 102 | 3 |
| 5 | 102 | 4 |
| 6 | 103 | 4 |
|-------------------------------------------|
this. reg_fk means table Region's ID, and I select reg_fk based on table Info. table Mapper already exists based on number of table Info's address, so all I have to do is read Info's address and put proper ID to Mapper.
This SQL is what I tried:
with region_info (region_id, info_id) as (
select region.id as region_id, info.id as info_id
from Region region
inner join Info info on
info.address like concat(concat('%', region.region_id), '%')
)
update Mapper mapper inner join Info info
on info_fk = info.id
set mapper.reg_fk = (
case
when info_fk = info.id then
(select region_id
from region_info
where region_info.info_id = info.id
)
end
)
where region_info.info_id = info.id;
It emits error, and I understood that I made a mistake that inside setting up mapper.reg_fk, there's multiple rows which I cannot set one 'mapper.reg_fk row' to multiple rows. But in this SQL sentence, if I join info and mapper on info_fk = info.id, then I should return multiple rows too. like in this example, info_fk = 100 doesn't make any error but info_fk = 101 then update 101 returns 2 rows. And also inside case sentence, I also get 2 rows (region_id 1 and 2) so it would be like
with join restriction, what to update in table Mapper
|-------------------------------------------|
| id | info_fk | reg_fk |
| 2 | 101 | |
| 3 | 101 | |
|-------------------------------------------|
what appears in case sentence
|--------------------|
| reg_fk |
| 1 |
| 2 |
|--------------------|
I want to properly update reg_fk to table Mapper. How do I do this?
Here you can simply build my example data and test my code (which is not working right now).
http://sqlfiddle.com/#!9/8c0c7d/4
Thank you.

Answer 1

with region_info (region_id, info_id) as (
select region.id as region_id, info.id as info_id
from Region region
inner join Info info on
info.address like concat(concat('%', region.region_id), '%')
)
update Mapper mapper inner join Info info
on info_fk = info.id inner join region_info on info.id = region_info.info_id
set mapper.reg_fk = (
(select region_id
from region_info
where region_info.info_id = info.id
LIMIT 1
)
)
last "where region_info.info_id = info.id;" is out of subquery. region_info is in subquery. so it can't find region_info. although you use "with" clause, if it is in "from" clause, you can't find it.
and you can use "LIMIT 1" or "any"(before subquery).