Question

I have a a table “wordlist”, with a score attributed to each word: either 1 or -1:

id | name | val
1, 'hello', 1,
2, 'world', -1
3, 'test', 1,
...

I also have a table “texts” containing texts:

id | text | score
1, 'hello world', 0
2, 'Lorem Ipsum Dolor Sit Amet...', 0
...

I’d like to update the field “score” from the table “texts” with this rule:

score = sum(wordlist.val) where each word of the sentence is present in the wordlist.

I tried this way, but it’s not working:

update texts as t set score=(select sum(val) from wordlist where word in (concat('\'', replace(t.text,' ','\',\''),'\'')))

I have more than 500K lines of data to process, so I’d rather use only MySQL, without using any PHP.

Thanks in advance if you have a solution!

I wish there was an explode() function in MySQL!

Answer 1

You could use FIND_IN_SET(), like this:

select
  texts.*, sum(val)
from
  texts left join wordlist
  on find_in_set(wordlist.name, replace(texts.`text`, ' ', ','))>0
group by texts.id

if you need to update your table, you could use this:

update texts inner join (
  select texts.id, sum(val) as score
  from texts left join wordlist
       on find_in_set(wordlist.name, replace(texts.`text`, ' ', ','))>0
  group by texts.id) s
  on texts.id=s.id
set texts.score=s.score