How can I use $ a to write the IDs of Zhang San and Li Si to the_id of Table B at the same time?

How can I use $ a to write the IDs of Zhang San and Li Si to the_id table A of Table B at the same time?
Id name
1 Zhang San
2 Li Si

$ A = 'James, James'
How can I use $ a to write the IDs of Zhang San and Li Si to the_id of Table B at the same time?
That is:
Table B
Id a_id
1, 2

Reply to discussion (solution)

Assume that the id of Table B is an auto-increment field.

Insert into Table B (a_id) select group_concat (id) from Table

No. I mean to use the variable $.

If $ a = 'Zhang San ';
Then the value of a_id is written to 1.

Insert into Table B (a_id) select group_concat (id) from table A where find_in_set (name, '$ ')

How can I modify update ??

Update Table B set a_id = (select group_concat (id) from table a where find_in_set (name, '$ '))