How to get the user with most comments from a table - mysql

Question

I am trying to get the user first name with the most comments. How can I do this?
Here are the tables.
The tables below are the setup for the database tables which I am trying to query.
CREATE TABLE User(
userid varchar(3),
firstname varchar(20),
lastname varchar(20),
age int,
PRIMARY KEY(userid)
)ENGINE=INNODB;
CREATE TABLE Comment(
commentid varchar(3),
userid varchar(3),
eventid varchar(3),
title varchar(20),
comment varchar(50),
PRIMARY KEY(commentid),
FOREIGN KEY(userid) REFERENCES AnonymousUser(userid),
FOREIGN KEY(eventid) REFERENCES Event(eventid)
)ENGINE=INNODB;
INSERT INTO User VALUES('U01','Charles','Darwin',99);
INSERT INTO User VALUES('U02','Keisha','Strawn',24);
INSERT INTO User VALUES('U03','Denise','Malcolm',59);
INSERT INTO User VALUES('U04','Dennis','Stewart',19);
INSERT INTO User VALUES('U05','Robert','Johns',45);
INSERT INTO User VALUES('U06','Marsha','Stewart',33);
INSERT INTO Comment VALUES ('C01','A01','E01','Boring Event','This event was boring');
INSERT INTO Comment VALUES ('C02','A02','E01','Nice Nice Event','This event was Nice');
INSERT INTO Comment VALUES ('C03','A03','E03','Wow','This event was Amazing');
INSERT INTO Comment VALUES ('C04','A01','E01','Very Sad','I missed this event');
The query I tried is
SELECT User.userid FROM User
JOIN comment ON comment.userid = user.userid
WHERE (SELECT COUNT(comment)
FROM comment = (SELECT MAX(userid) FROM comment);

Answer 1

SELECT
userid
FROM
comment
GROUP BY userid
ORDER BY count(userid) DESC
LIMIT 1;
Edit: oh, you need the username. Try this:
SELECT firstname
FROM user
WHERE userid = (
SELECT
userid
FROM
comment
GROUP BY userid
ORDER BY count(userid) DESC
LIMIT 1
);

Answer 2

Query to get firstname with most comments is
select a.firstname, max(a.comment_count) from (
select u.firstname, count(c.commentid) comment_count
from user u join comment c on u.userid = c.userid
group by u.firstname
)a;
That said, I noticed
One of the constraints on table 'comment' is pointing to a table 'AnonymousUser' FOREIGN KEY(userid) REFERENCES AnonymousUser(userid). You have not shared the create table statement for that table.
I had to remove this constraint from table definition in order to successfully create this table in my database
CREATE TABLE Comment(
commentid varchar(3),
userid varchar(3),
eventid varchar(3),
title varchar(20),
comment varchar(50),
PRIMARY KEY(commentid)
);
You dataset for table 'comment' has no userid matching 'user.userid' values
I updated the 'comment' table inserts so I could get some result when executing my query.
INSERT INTO Comment VALUES ('C01','U01','E01','Boring Event','This event was boring');
INSERT INTO Comment VALUES ('C02','U01','E01','Nice Nice Event','This event was Nice');
INSERT INTO Comment VALUES ('C03','U03','E03','Wow','This event was Amazing');
INSERT INTO Comment VALUES ('C04','U06','E01','Very Sad','I missed this event');