MySQL multiple SELECT statements in one query - mysql

Question

I'm storing some information in a MySQL table including a date without time.
The date format is a string looking like this: "25.08.2016" (Day.Month.Year).
I want to select the top 50 records from a table descending by a column, but I only want to display the rows with a specific column entry (date).
It is a ranking system and I want to update inactive people.
I would need to combine these 3 queries:
SELECT * FROM `rank` ORDER BY `rank`.`Score` DESC LIMIT 0 , 50;
SELECT * FROM `rank` WHERE NOT (`TimeStamp1` = DATE_FORMAT(NOW(), '%d.%m.%Y') OR `TimeStamp1` = DATE_FORMAT(DATE_SUB(NOW(), INTERVAL 1 DAY), '%d.%m.%Y'));
UPDATE `rank` SET `inactive` = '1';
Selecting the top 50 people.
Selecting the inactive people of the first query.
Updating the people to inactive.
The most Score is rank 1 and that's why I need DESC, I only want to mark the top 50 people as inactive nothing below, below 50 those people are irrelevant that's why I can't use a statement like this:
SELECT * FROM `rank` WHERE NOT (`TimeStamp1` = DATE_FORMAT(NOW(), '%d.%m.%Y') OR `TimeStamp1` = DATE_FORMAT(DATE_SUB(NOW(), INTERVAL 1 DAY), '%d.%m.%Y')) ORDER BY `rank`.`Score` DESC LIMIT 0 , 50
Yes, it would select 50 rows but not the top 50.
BTW I'm doing it in php.
And I could solve the problem by fetching:
SELECT * FROM `rank` ORDER BY `rank`.`Score` DESC LIMIT 0 , 50;
Then storing the Accound IDs to an array, then query:
SELECT * FROM `rank` WHERE NOT (`TimeStamp1` = DATE_FORMAT(NOW(), '%d.%m.%Y') OR `TimeStamp1` = DATE_FORMAT(DATE_SUB(NOW(), INTERVAL 1 DAY), '%d.%m.%Y')) ORDER BY `rank`.`Score` DESC LIMIT 0 , 50;
And compare the Accound IDs to the other result, when no match is found I just break the loop.
Can't I just do it with pure MySQL? Can't I query a thing and then filter the results?
Please help me, any more questions?

Answer 1

Here's my Answer.
UPDATE rank AS target
INNER JOIN (
SELECT w.id
FROM rank AS w
INNER JOIN rank AS e ON e.id = w.id
WHERE (w.`TimeStamp1` = DATE_FORMAT(NOW(), '%Y-%m-%d') OR w.`TimeStamp1` = DATE_FORMAT(DATE_SUB(NOW(), INTERVAL 1 DAY),'%Y-%m-%d'))
ORDER BY w.`Score` DESC
LIMIT 50
) AS source ON source.id = target.id
SET inactive = 1;

Answer 2

One way of executing queries sequentially is by using transaction.
But that won't combine your queries into one.
BEGIN TRANSACTION;
SELECT *
FROM `rank`
ORDER BY `rank`.`Score` DESC LIMIT 0 , 50;
SELECT *
FROM `rank`
WHERE NOT (`TimeStamp1` = DATE_FORMAT(NOW(), '%d.%m.%Y') OR `TimeStamp1` = DATE_FORMAT(DATE_SUB(NOW(), INTERVAL 1 DAY), '%d.%m.%Y'));
UPDATE `rank` SET `inactive` = '1';
COMMIT;

Answer 3

Maybe this might be a combination of the three queries:
update rank r
set r.inactive = 1
from
(select a.account_id from rank a
join (select account_id from rank order by rank.score desc limit 0, 50) b on (a.account_id = b.account_id )
where (a.`TimeStamp1` = DATE_FORMAT(NOW(), '%d.%m.%Y') OR a.`TimeStamp1` = DATE_FORMAT(DATE_SUB(NOW(), INTERVAL 1 DAY), '%d.%m.%Y'))) l
where r.account_id = l.account_id
Let me know if anything fails :)
Edit: swapped rank_id with account_id