MySQL update table based on another tables value

I have a two tables,

Here is my first table,

ID		SUBST_ID		CREATED_ID
1		031938			TEST123
2		930111			COOL123
3		000391			THIS109
4		039301			BRO1011
5		123456			COOL938
...		...				...

This is my second table,

ID		SERIAL_ID		BRANCH_ID
1		039301			NULL
2		000391			NULL
3		123456			NULL
...		...				...

I need to some how update all rows within my second table using data from my first table.

It would need to do this all in one update query.

Both SUBST_ID and SERIAL_ID match, it needs to grab the created_id from the first table and insert it into the second table.

So the second table would become the following,

ID		SERIAL_ID		BRANCH_ID
1		039301			BRO1011
2		000391			THIS109
3		123456			COOL938
...		...				...

Thank you for your help and guidance.

UPDATE TABLE2
       JOIN TABLE1
       ON TABLE2.SERIAL_ID = TABLE1.SUBST_ID
SET    TABLE2.BRANCH_ID = TABLE1.CREATED_ID;

In addition to Tom's answer if you need to repeat the operation frequently and want to save time you can do:

UPDATE TABLE1
       JOIN TABLE2
       ON TABLE1.SUBST_ID = TABLE2.SERIAL_ID
SET    TABLE2.BRANCH_ID = TABLE1.CREATED_ID
WHERE TABLE2.BRANCH_ID IS NULL

UPDATE TABLE2
       JOIN TABLE1
       ON TABLE1.SUBST_ID = TABLE2.SERIAL_ID
SET    TABLE2.BRANCH_ID = TABLE1.CREATED_ID 
WHERE TABLE2.BRANCH_ID IS NULL or TABLE2.BRANCH_ID='';

I think this should work

UPDATE secondTable
JOIN firsTable ON secondTable.SERIAL_ID = firsTable.SUBST_ID
SET BRANCH_ID = CREATED_ID

It is very simple to update using Inner join query in SQL .You can do it without using FROM clause. Here is an example :

    UPDATE customer_table c 

      INNER JOIN  
          employee_table e
          ON (c.city_id = e.city_id)  

    SET c.active = "Yes"

    WHERE c.city = "New york";

Using INNER JOIN:

UPDATE TABLE1
INNER JOIN TABLE2 ON TABLE1.SUBST_ID = TABLE2.SERIAL_ID
SET TABLE2.BRANCH_ID = TABLE1.CREATED_ID;

Another alternative solution like below: Here I am using WHERE clause instead of JOIN

UPDATE 
	TABLE1,
	TABLE2
WHERE
	TABLE1.SUBST_ID = TABLE2.SERIAL_ID
SET 
	TABLE2.BRANCH_ID = TABLE1.CREATED_ID;

You can use this too:

update TABLE1 set BRANCH_ID = ( select BRANCH_ID from TABLE2 where TABLE1.SUBST_ID = TABLE2.SERIAL_ID)

but with my experience I can say that this way is so slow and not recommend it!