Slava Rozhnev

alter table user_groups add unique index (username, group_id);

SELECT p.*, category_titles, filter_titles
FROM products as p
LEFT JOIN (
  	SELECT product_id, json_arrayagg(c.title) category_titles from  product_category as pc
	JOIN categories as c ON pc.category_id=c.id
  	GROUP BY product_id
) pc ON  p.id=pc.product_id
JOIN (
  	SELECT product_id, json_arrayagg(f.title) filter_titles 
  	FROM product_filter as pf
	JOIN filters as f ON pf.filter_id=f.id
  	GROUP BY product_id
) pf ON p.id=pf.product_id
WHERE p.id='2'

UPDATE users 
INNER JOIN api_tokens ON api_tokens.user_id=users.id 
SET users.first_name = (?),  users.last_name = (?),  users.email = (?)  
WHERE api_tokens.token IN (?)

UPDATE `notice` 
SET `time_update` = ?, `current_value` = ? 
WHERE `id` = ? AND  `time_update` = `time`;

SELECT id, (c1=1) + (c2=0) + (c3=1) + (c4=1) + (c5=1) + (c6=1) + (c7=1) FROM test 
WHERE ((c1=1) + (c2=0) + (c3=1) + (c4=1) + (c5=1) + (c6=1) + (c7=1)) = 6
;

select count(*) as count 
from table 
where toUserID = 6482 
group by idCom
having count(*) > 3;

<?php
$mysqli->query("SET NAMES 'utf8'");

$mysqli->query("CREATE TABLE `geolocal` (
            `id` INT AUTO_INCREMENT,
            `names` VARCHAR(50),
            `pass` VARCHAR(20),
            `email` VARCHAR (50),
            PRIMARY KEY(`id`)
            )"
);

$mysqli->query(
    "INSERT INTO `geolocal` (`names`,  `pass`,  `email`) VALUES ('spiderman',  'pautinka',  's.pider@list.ru')"
);

$mysqli->close();

$stmt = $mysqli->prepare("UPDATE req 
	SET balance = balance - ? 
	WHERE card =? AND code = ? ;");
$stmt->bind_param("sss", $cost, $card, $code);

// set parameters and execute
$cost = $_GET['cost'];
$card = $_POST['card'];
$code = $_POST['code'];

$stmt->execute();

SELECT userid
FROM tbl 
GROUP BY userid
HAVING COUNT(userid) = 1;