Selecting from 2 different tables

Question

is this possible?
i just want to select from two different tables in one select statement and they have the same WHERE clause

Answer 1

SELECT
  a.pkggrp,
  a.pkgtype,
  a.area,
  a.process,
  a.ww,
  count(a.ww) as LOTSGATED,
  sum(a.samplesize) as SUMSAMPLESIZE,
  sum(a.total_defects) as SUMTOTALDEFECTS,
  sum(case a.auditresult when 'pass' then 1 else 0 end) COUNTPASS,
  sum(case a.auditresult when 'fail' then 1 else 0 end) COUNTFAIL,
  case sum(case a.auditresult when 'fail' then 1 else 0 end)
    when 0 then 0
  else round(sum(case a.auditresult when 'fail' then 1 else 0 end) / count(a.ww) * 100,2)
    end LRR,
  case sum(case a.auditresult when 'fail' then 1 else 0 end)
    when 0 then 0
  else round(sum(case a.auditresult when 'fail' then 1 else 0 end) / sum(a.samplesize) * 1000000,0)
    end PPM,
  count(c.itrnum)
FROM
  t_prodproc_monitoring a, t_itr c
WHERE
  a.ww=c.ww
  and a.ww between 1 and 50
  and c.ww between 1 and 50
GROUP BY
  a.pkggrp,
  a.pkgtype,
  a.area,
  a.process,
  a.ww
ORDER BY
  a.pkggrp,
  a.pkgtype,
  a.area,
  a.process,
  a.ww ascthis gave me a
"c". "ww": invalid identifier