php - MYSQL count based off of two tables -

sorry asking this, haven't found answer i'm trying anywhere!

basically, have database 2 tables. below or 2 examples i'll use:

table 1:

process id  date ---------- -----------          1  2008/08/21          2  2008/08/23          3  2008/08/21 

table 2:

process id qty ---------- ---          1   1          2   4          3   6 

basically, in php select table 1, , find processes occur today (in example i'll 21st of august). want take process ids, , match them in table 2 , give count of quantities.

the end result i'm trying figure out in example how output "7" using php select processes happened today in 1 table, add corresponding process quantities in table.

select sum(t2.qty) table1 t1 join table2 t2 on t1.pid = t2.pid t1.date = '2008/08/21'