Update a table use result of another query in Postgres

Question

I have a 2 table like this:

table1 : ( time, value, id ), table2 :( time, value, id, ... )

I need to update table1 with a result of a query on table2 based on id , for example the query can be:

SELECT * from table2 where value > 2

and this query returns more than hundreds of rows,

I need update table1 with these rows based on id ( set time=q.time, value=q.value where id=q.id ) is it possible with sql query?

I don't need UPSERT as I'm sure I have same id in both tables, just need update

Answer 1

Postgres supports a FROM clause for UPDATE :

update table1
   set time = q.time, 
       value = q.value
from table2 q
where table2.id = table1.id
  and table2.value > 2;

Answer 2

SELECT * 
into temp buffer     
from table2 
where value > 2;


insert into table1(list of columns to be updated)
select (list of columns to be selected)
from buffer;

NOTE___ --buffer is a temporary table that stores the output of the main query -- make sure both tables (table1 and table2) have the same columns and are arranged in the same order