How to find most popular word occurrences in MySQL?

Question

I have a table called results with 5 columns.

I\'d like to use the title column to find rows that are say: WHERE title like \'%for sale%\

Answer 1

Here is working SQL Fiddle: http://sqlfiddle.com/#!9/0b0a0/32

Let's start with two tables - one for texts and one for numbers:

CREATE TABLE text (`title` varchar(29));

INSERT INTO text
    (`title`)
VALUES
    ('cheap cars for sale'),
    ('house for sale'),
    ('cats and dogs for sale'),
    ('iphones and androids for sale'),
    ('cheap phones for sale'),
    ('house furniture for sale')
;

CREATE TABLE iterator (`index` int);

INSERT INTO iterator
    (`index`)
VALUES
    (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12),(13),(14),(15),
    (16),(17),(18),(19),(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),(30)
;

The second table, iterator must contains numbers from 1 to N where N higher or equal to the lenght of the longest string in text.

Then, run this query:

select
  words.word, count(*) as `count`
from 
(select
  substring(concat(' ', t.title, ' '), i.index+1, j.index-i.index) as word
from
  text as t, iterator as i, iterator as j
where
    substring(concat(' ', t.title), i.index, 1) = ' '
and substring(concat(t.title, ' '), j.index, 1) = ' '
and i.index < j.index
) AS words
where
    length(words.word) > 0
and words.word not like '% %'
group by words.word
order by `count` desc, words.word asc

There are two selects. Outer one simply groups and counts single words (words of length greater than 0 and without any spaces). Inner one extracts all strings starting from any space character and ending with any other space character, so strings aren't words (despite naming this subquery words) because they can contain other spaces than starting and ending one.

Results:

word    count
for     6
sale    6
and     2
cheap   2
house   2
androids    1
cars    1
cats    1
dogs    1
furniture   1
iphones     1
phones  1