How to batch update mysql according to respective conditions

Question

There are two tables, A is the detailed table
id uid cost

1. 1. 0

2. 1. 1

3. 1. 4

4. 1. 3

Now we need to group the data with cost greater than 0 in the table according to uid and update it to another table

select uid,count(cost) as count from A group by uid where cost > 0

This is the statement taken out. Is there any way to update the query results to another table based on uid in one sentence?

Answer 1

update B b set b.col=(select count(a.cost) as count from A a where cost > 0 and a.uid=b.uid group by uid)