Mysql updating multiple tables
There is one downside: the rows are not locked in primary key order.
This may help explain the occasional deadlock we get on this table (see my article about a “little-known” way to cause a deadlock).
Error Banner.fade_out.modal_overlay.modal_overlay .modal_wrapper.modal_overlay [email protected](max-width:630px)@media(max-width:630px).modal_overlay .modal_fixed_close.modal_overlay .modal_fixed_close:before.modal_overlay .modal_fixed_close:before.modal_overlay .modal_fixed_close:before.modal_overlay .modal_fixed_close:hover:before. In order to do this, each process tries to update some rows so table or not.The query to claim a set of rows for a process needs to update the ten highest-priority unclaimed rows for eligible clients.We have used a table called 'item' to apply the query: Table Name : item Structure : item_code varchar(20), value int(11), quantity int(11) where item_code is the primary key.In the following rows of item table, 'value' column which is marked with red rectangle will be updated.Since it needs to access more than one table, and needs to order and limit the results, at first it seems you can’t do this query at all, because -- @process_id is actually passed in as a parameter -- set @process_id = 17603; update work_to_do set processor = @process_id where processor = 0 and client in (select client from eligible_client) order by priority desc limit 10 the query completes in a 0.13 seconds, but with 5,000 the correlated subquery becomes a real performance problem; it takes 9.8 seconds, which is very slow for this machine. To eliminate the badly optimized subquery, you need to rewrite the subquery as a join, but how can you do that and retain the update work_to_do as target inner join ( select w.client, work_unit from work_to_do as w inner join eligible_client as e on e.client = w.client where processor = 0 order by priority desc limit 10 ) as source on source.client = target.client and source.work_unit = target.work_unit set processor = @process_id; table.If this article was useful to you, subscribe via e-mail or feeds to receive future articles conveniently and free..action_button.action_button:active.action_button:hover.action_button:focus.action_button:hover.action_button:focus .count.action_button:hover .count.action_button:focus .count:before.action_button:hover .count:before.u-margin-top--lg.u-margin-left--sm.u-flex.u-flex-auto.u-flex-none.bullet. The following My SQL statement will update pub_lang column with NULL if purch_price is more than 50.In this statement, other columns are also updated with respective new values.