Impossible to execute a query

I have an issue and not sure how to fix. I am entering a custom query into the Custom SQL Query box and it returns and error that states:
Invalid JSON: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT * FROM pm1_users' at line 1. Any ideas?

what is the query you are entering?

it is impossible to tell why the error is occurring without knowing the query you are running to create the error.

Any query like :SELECT * FROM pm1_users

I tried to use SELECT DISTINCT UserEmail FROM pm1_users

I can't use any query

the start of the query is already defined as:
SELECT * FROM pm1_users

the input box is for adding a custom where clause:
WHERE UserID = 2

How to use a Distinct option ?

When I add WHERE UserEmail > "c"

I got an error

use GROUP BY instead of Distinct.


UserEmail > "c" is not a valid syntax

the > operator stands for Greater Than. You cannot perform that sort of math operation on a string, only on a number:

UserID > 5 would be valid

But how can I select only one email ( for exemple when two different users have the same email) by users using GROUP BY

I want to select:

SELECT DISTINCT UserEmail FROM pm1_users

SELECT * FROM pm1_users GROUP BY UserEmail

does the same thing