mysql update column with value from another table

Question

In addition to this answer if you need to change tableB.value according to tableA.value dynamically you can do for example:

UPDATE tableB
INNER JOIN tableA ON tableB.name = tableA.name
SET tableB.value = IF(tableA.value > 0, tableA.value, tableB.value)
WHERE tableA.name = 'Joe'

you need to join the two tables:

for instance you want to copy the value of name from tableA into tableB where they have the same ID

UPDATE tableB t1 
        INNER JOIN tableA t2 
             ON t1.id = t2.id
SET t1.name = t2.name 
WHERE t2.name = 'Joe'

UPDATE 1

UPDATE tableB t1 
        INNER JOIN tableA t2 
             ON t1.id = t2.id
SET t1.name = t2.name 

UPDATE 2

UPDATE tableB t1 
        INNER JOIN tableA t2 
             ON t1.name = t2.name
SET t1.value = t2.value

Second possibility is,

UPDATE TableB 
SET TableB.value = (
    SELECT TableA.value 
    FROM TableA
    WHERE TableA.name = TableB.name
);

    UPDATE    cities c,
          city_langs cl
    SET       c.fakename = cl.name
   WHERE     c.id = cl.city_id