nozzy

select distinct a.name, b.way, c.location ...

SELECT
....
FROM MYTABLE
FOR JSON AUTO

$result = $mysqli -> query(....)

Не по сути вопроса, а по оптимизации. Почему бы не сделать один update?

UPDATE users set rank = (%s), pin = (%s) where teleid=(%s)

select 
t1.AUTHOR,
t1.total
from
(
SELECT AUTHOR, count(*) as total
FROM POSSESSION
INNER JOIN BOOKS ON BOOK_ID = BOOKS.ID
WHERE TAKING_DATE > (CURRENT_DATE - INTERVAL '1 year')
GROUP BY AUTHOR
)  t1
where t1.total =
(
select
max(t2.total)
from
(
SELECT AUTHOR, count(*) as total
FROM POSSESSION
INNER JOIN BOOKS ON BOOK_ID = BOOKS.ID
WHERE TAKING_DATE > (CURRENT_DATE - INTERVAL '1 year')
GROUP BY AUTHOR
) t2
)

select
t1.*,
t2.*,
t3.*
from mainTable t1
inner join mainTable_table1 t2 on t2.id_mainTable = t1.id_mainTable 
inner join table1 t3 on t3.id_table1 = t2.id_table1

select username,
sum(Amount1  + Amount2 + Amount3) as total
from my_table
group by username
order by total desc limit 20

update table1 t1
left join table2 t2 on t2.`name` = t1.`name`
set t1.`name` = null
where t2.`name` is null

select
t1.*
t2.name,
t2.surname
from reviews t1
left join users t2 on t2.id = t1.user_id

select
t1.name_goods,
t2.name_subcat,
t3.name_cat
from goods t1
left join subcategory t2 on t2.id_subcat = t1.id_subcat
left join category t3 on t3.id_cat = t1.id_cat

select 
iduser,
sum(reward)
from ochk 
where EXTRACT(YEAR_MONTH FROM dateadd) = EXTRACT(YEAR_MONTH FROM CURRENT_DATE()) 
group dy iduser;

Уберите id из запроса, autoincrement добавится автоматически

INSERT INTO `product_comments` (`product_slug`, `product_id`, `user_id`, `created_at`, `updated_at`, `content`) VALUES ('крем-для-рук-и-ногтей',1,2,'2019-04-08 13:25:31.000000','2019-04-08 13:25:31.000000','Крем вообще супер.')

select * from table where date is null
union
select * from table where date = '20190101'