how to update a column in psql with values from other table code example

Example 1: inner join update

UPDATE 
    t1
SET 
    t1.c1 = t2.c2,
    t1.c2 = expression,
    ...   
FROM 
    t1
    [INNER | LEFT] JOIN t2 ON join_predicate
WHERE 
    where_predicate;

Example 2: sql update with field from another table

UPDATE table1 
   SET price=(SELECT price FROM table2 WHERE table1.id=table2.id);