Select All Distinct Words in Column MYSQL - mysql

Question

I have a column in which is stored nothing but text separated by one space. There may be one to maybe 5 words in each field of the column. I need a query to return all the distinct words in that column.
Tried:
SELECT DISTINCT tags FROM documents ORDER BY tags
but does not work.
To Elaborate.
I have a column called tags. In it I may have the following entries:
Row 1 Red Green Blue Yellow
Row 2 Red Blue Orange
Row 3 Green Blue Brown
I want to select all the DISTINCT words in the entire column - all fields. It would return:
Red Green Blue Yellow Orange Brown
If I counted each it would return:
2 Red
2 Green
3 Blue
1 Yellow
1 Brown
1 Orange

Answer 1

To fix this I ended up creating a second table where all keywords where inserted on their own row each along with a record key that tied them back to the original record in the main data table. I then just have to SELECT DISTINCT to get all tags or I can SELECT DISTINCT with a WHERE clause specifying the original record to get the tags associated with a unique record. Much easier.

Answer 2

There is not a good solution for this. You can achieve this with JSON functions as of 5.6, I think, but it's a little tricky until 8.0, when mySQL added the JSON_TABLE function, which can convert json data to a table like object and perform selects on it, but how it will perform is dependent on your actual data. Here's a working example:
CREATE TABLE t(raw varchar(100));
INSERT INTO t (raw) VALUES ('this is a test');
You will need to strip the symbols (commas, periods, maybe others) from your text, then replace any white text with ",", then wrap the whole thing in [" and "] to json format it. I'm not going to give a full featured example, because you know better than I do what your data looks like, but something like this (in its simplest form):
SELECT CONCAT('["', REPLACE(raw, ' ', '","'), '"]') FROM t;
With JSON_TABLE, you can do something like this:
SELECT CONCAT('["', REPLACE(raw, ' ', '","'), '"]') INTO #delimited FROM t;
SELECT *
FROM JSON_TABLE(
#delimited,
"$[*]"
COLUMNS(Value varchar(50) PATH "$")
) d;
See this fiddle: https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=7a86fcc77408ff5dfec7a805c6e4117a
At this point you have a table of the split words, and you can replace SELECT * with whatever counting query you want, probably SELECT Value, count(*) as vol. You will also need to use group_concat to handle multiple rows. Like this:
insert into t (raw) values ('this is also a test'), ('and you can test it');
select concat(
'["',
replace(group_concat(raw SEPARATOR '","'), ' ', '","'),
'"]'
) into #delimited from t;
SELECT Value, count(*) as vol
FROM JSON_TABLE(
#delimited,
"$[*]"
COLUMNS(Value varchar(50) PATH "$")
) d
GROUP BY Value ORDER BY count(*) DESC;
If you are running <8.0, you can still accomplish this, but it will take some hackiness, like generating an arbitrary list of numbers and constructing the paths dynamically from that.