On 2/16/2017 6:25 PM, Patrick B wrote:
how can I update a row with newest id from another table if it exists
somewhere else?
Example:
*table test1*
* id (primary key)
* id_user_bill
* clientid
*table test2*
* item_id
* userid (there are duplicated rows here)
* clientid
* id (primary key)
-- finding the dup records
INSERT INTO test2_results
SELECT
item_id,
userid
count(*) as dup_count,
MAX(id) as recent_id
FROM
test2
GROUP BY
item_id,
userid
HAVING COUNT(*) > 1;
if test1.id_user_bill = test2.id <http://test2.id>, then
update test1.id_user_bill with test2_results.recent_id
UPDATE test1 SET test1.id_user_bill = test2_results.recent_id FROM
test2_results WHERE test1.id_user_bill = test2_results.item_id;
(at least if I interpret what you're asking correctly, there's some
errors there, for instance, there's no such field as test2.id shown, and
the schema of test2_results is undefined, too)
'from' works very much like a INNER JOIN, and the WHERE clause has to
include the join condition.
--
john r pierce, recycling bits in santa cruz
