Sql find only one hashtag not two

Question

How to find in a MySQL database?:

# Some title 

(In a text field most of the titles are:
## Some title.
But there are some mistakes with only one #. How can I find them in a big database?. I know that they are only in the field text_post)

I could find that it could be something like:

SELECT * FROM blog
WHERE text_post LIKE '%#%'

But, how can I find when there is only one # and not two?

If I understand, it is not possible to use regex here. Is that right?

Answer 1

Add an extract clause to eliminate the double ##.

SELECT * 
FROM blog
WHERE (text_post LIKE '%#%' AND text_post NOT LIKE '%##%')

Answer 2

^    - Beginning of line
#    - hashtag
[^#] - Any character other than hashtag
|    - OR operator
$    - End of line

---

select  *
from    blog
where   text_post rlike '^#([^#]|$)'