Sql queries 10 pieces of data for each category

a table 

a_id name 
1    1

2    2

3    3

4    4

5    5

b table 

b_id name a_id
1    a    1

2    b    1

3    c    1

4    d    2

5    e    2

how to write the sql statement to query 10 pieces of data for each category

find an array structure similar to the following: 

array(
    array(
        "a_id"=>1,
        "a_name"=>1
        "b_list"=>array{
            array(
                "b_id"=>1,
                "b_name"=>a,
                "a_id"=>1,
            ),
            
            array(
                "b_id"=>1,
                "b_name"=>a,
                "a_id"=>1,
            ),
        }
    },
    array(
        "a_id"=>1,
        "a_name"=>1
        "b_list"=>array{
            array(
                "b_id"=>1,
                "b_name"=>a,
                "a_id"=>1,
            ),
            
            array(
                "b_id"=>1,
                "b_name"=>a,
                "a_id"=>1,
            ),
        }
    },
);

I"m not sure if this structure can be checked by mysql. How efficient is it? I want to toss about (A V A)

.
Php mysqli
Mar.24,2022

A way of using grouping and trickery
SELECT * FROM b WHERE b.id in (
SELECT GROUP_CONCAT (b.id) FROM an INNER JOIN b on a.id = b.aid GROUP BY a.id HAVING COUNT (*) < 11
)

The idea of

is to get 10 id of the b table of the group, then look it up in the model text, and finally get 10

of each group.

if it is up to date, sort it using

UNION query?

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1e86e1f-e0f.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e86e1f-e0f.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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