MySQL 8.0

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create table messages(sent varchar(200), verif int);
insert into messages values
	
          
	
             ('HI' , null),

             ('HI alex how are you' , null),

             ('bye' , null);
select * from messages;


sent
verif


HI
null

HI alex how are you
null

bye
null


UPDATE messages set sent = TRIM(sent);
UPDATE messages set sent = REGEXP_REPLACE(sent,' +',' ')
with recursive cte as (
	select 
		substring(concat(sent, ' '), 1, locate(' ', concat(sent, ' '))) word,
		substring(concat(sent, ' '), locate(' ', concat(sent, ' ')) + 1) sent
	from messages
	union all
	select 
		substring(sent, 1, locate(' ', sent)) word,
		substring(sent, locate(' ', sent) + 1) sent
	from cte
	where locate(' ', sent) > 0
)
select row_number() over(order by count(*) desc, word) wid, word, count(*) freq
from cte 
group by word
order by wid


wid
word
freq


1
HI
2

2
alex
1

3
are
1

4
bye
1

5
how
1

6
you
1