Count occurrences of distinct values with multiple tables - php

Question

I have 3 tables in a database that have similar values and the same table structure. I am trying to get the number of occurrences of each value by unique user.
DB Structure
View on SQLFiddle
TABLE_1
user | value | id
TABLE_2
user | value | id
TABLE_3
user | value | id
I can run the following MySQL command to retrieve the desired results on 1 table at a time.
SELECT value,COUNT(*) as count FROM TABLE_1 GROUP BY value ORDER BY count DESC;
I need to run this command across the three tables at once in order to retrieve the unique occurrences of "value" among a list of "users" that contains numerous duplicates.

Answer 1

Given your comments, since you want to remove duplicates, use UNION to combine the data from the tables together:
SELECT value, COUNT(*) as count
FROM (
SELECT user, value, id
FROM TABLE_1
UNION
SELECT user, value, id
FROM TABLE_2
UNION
SELECT user, value, id
FROM TABLE_3 ) t
GROUP BY value
ORDER BY count DESC;
Updated Fiddle

Answer 2

You need to use UNION -
SELECT value, COUNT(*) as count
FROM (
SELECT user, value, id
FROM TABLE_1
UNION
SELECT user, value, id
FROM TABLE_2
UNION
SELECT user, value, id
FROM TABLE_3 ) tables
GROUP BY value
ORDER BY count DESC;
Output -
+-------+-----+
|car |8 |
|boat |4 |
|truck |3 |
|house |2 |
|skates |1 |
|bike |1 |
+-------+-----+

Answer 3

to go along with the comments this is what I would recommend you do.
setup:
CREATE TABLE members (
id int(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
username varchar(255),
);
INSERT INTO members (username)
SELECT DISTINCT user FROM table1
UNION SELECT DISTINCT user FROM table2
UNION SELECT DISTINCT user FROM table3;
altering:
ALTER table1
ADD COLUMN user_id INT(10)
ADD INDEX `user_id` (`user_id`);
ALTER table2
ADD COLUMN user_id INT(10)
ADD INDEX `user_id` (`user_id`);
ALTER table3
ADD COLUMN user_id INT(10)
ADD INDEX `user_id` (`user_id`);
updating:
UPDATE table1 t,
JOIN members m ON m.username = t.username
SET t.user_id = m.id;
UPDATE table2 t,
JOIN members m ON m.username = t.username
SET t.user_id = m.id;
UPDATE table3 t,
JOIN members m ON m.username = t.username
SET t.user_id = m.id;
removing non normalized data
ALTER table1
DROP user;
ALTER table2
DROP user;
ALTER table3
DROP user;
now you can also set up foreign key contstraints on the user_id and id columns if you would like.
but to query a total count you can just join the tables.. make sure you add an index on each of the id fields so it will join properly.
SELECT your_stuff
FROM members m
LEFT JOIN table1 t1 ON t1.user_id = m.id
LEFT JOIN table2 t2 ON t2.user_id = m.id
LEFT JOIN table3 t3 ON t3.user_id = m.id