Replace all occurrences of subquery in select result - mysql

Question

Working on an export from a Sparx EA database in MySQL.
The database contains objects that have notes
select o.Note from t_object o
The result could be
Note
Contains reference to term1 and term2
Another note that mentions term1 only
A note that doesn't mention any terms
There is also a glossary that I can query like this
select g.TERM
from t_glossary g
union
select o.Name
from t_diagram d
join t_diagramobjects dgo
on dgo.Diagram_ID = d.Diagram_ID
join t_object o
on o.Object_ID = dgo.Object_ID
where 1=1
and d.styleEx like '%MDGDgm=Glossary Item Lists::GlossaryItemList;%'
The result of this query
TERM
term1
term2
The requirement is that I underline each word in the notes of the first query that is an exact match to one of the terms in the second query. Underlining can be done by enclosing the word in <u> </u> tags
So the final query result should be
Note
Contains reference to <u>term1</u> and <u>term2</u>
Another note that mentions <u>term1</u>only
A note that doesn't mention any terms
Is there any way to do this in a select query? (so without variables, temp tables, loops, and all that stuff)

Answer 1

I think regular expressions might be a better approach. For your example, you want:
select regexp_replace(note, '(term1|term2)', '<u>$1</u>')
from t_object;
You can easily construct this in MySQL as:
select regexp_replace(note, pattern, '<u>$1</u>')
from t_object cross join
(select concat('(', group_concat(term separator '|'), ')') as pattern
from t_glossary
) g;
Here is a db<>fiddle.
Regular expressions have a key advantage that they give you more flexibility on the word boundaries. The above replaces any occurrence of the terms, regardless of surrounding characters. But you can adjust that using the power of regular expressions.
I might also suggests that such replacement could be done -- using regular expressions -- at the application layer.

Answer 2

Here I have replace all the TERM from t_glossary table in note column from t_object table with <ul>Term</ul>
Schema:
create table t_object(note varchar(500));
insert into t_object
select 'Contains reference to term1 and term2' as Note
union all
select 'Another note that mentions term1 only'
union all
select 'A note that doesn''t mention any terms';
create table t_glossary (TERM varchar(500));
insert into t_glossary
select 'term1 '
union all
select 'term2';
Query:
WITH recursive CTE (note, note2, level) AS
(
SELECT note, note , 0 level
FROM t_object
UNION ALL
SELECT CTE.note,
REPLACE(CTE.note2, g.TERM, concat(' <u>', g.term , '</u> ')), CTE.level + 1
FROM CTE
INNER JOIN t_glossary g ON CTE.note2 LIKE concat('%' , g.TERM , '%') and CTE.note2 not like concat('%<u>', g.term , '</u>%')
)
SELECT DISTINCT note2, note, level
FROM CTE
WHERE level =
(SELECT MAX(level) FROM CTE c WHERE CTE.note = c.note)
Output:
note2
note
level
A note that doesn't mention any terms
A note that doesn't mention any terms
0
Another note that mentions <u>term1 </u> only
Another note that mentions term1 only
1
Contains reference to <u>term1 </u> and <u>term2</u>
Contains reference to term1 and term2
2
db<>fiddle here