SQL statement to delete a user in moodle

Which SQL statement can I use to delete a user in moodle. I don't think

"delete from mdl_user where id=1234" 

is insufficient.
Thanks

I wouldn't recommend deleting a user via SQL

There are lots of internal checks and event triggers, as well as the likelihood of breaking database integrity

Delete a user manually

Site admin > Users > Browse list of users > [select user to delete]

Delete several users at a time

If you need to delete several users at a time then you can use a csv file

Create a csv file like this with 1 in the deleted column

username,firstname,lastname,email,deleted
student1,Student,One,s1@example.com,1

You could use SQL to build the csv

SELECT username,firstname,lastname,email,1 AS deleted
FROM mdl_user
WHERE ...

Then go to Site admin > Users > Upload users

Select "Update existing users" for Upload type

and "Yes" for Allow deletes

Delete users via command line

There is a command line tool called Moosh that allows deletion from the command line

moosh user-delete username1 username2

Moosh isn't included with Moodle so you will need to install it

https://moosh-online.com/

PHP code to delete a user

Or create some code to delete users using the Moodle function delete_user()

$sql = "SELECT *
        FROM {user}
        WHERE ...";

$users = $DB->get_records_sql($sql);

foreach ($users as $user) {
    delete_user($user);
}

There is no SQL statement for deleting a user in Moodle - there are far too many different steps that are taken in order to properly delete a user, so you should always use the PHP function for deleting users.

If you need to do this from outside of Moodle itself, then you should look at configuring and using the "core_user_delete_users" webservice function.

See https://docs.moodle.org/en/Using_web_services for details of how to use webservice functions to communicate with your Moodle server.