Ok, but in this way I can only detect if it's done ONE type of operation, for example if I add a row and I remove an another one with this query I detect "no difference". The principal point of the query that I want is to say "which" rows are changed (added or deleted). I think it's not a easy query (or set of queries), but I want to create one for this goal.
However thanks for the hint about the difference between COUNT(1) and COUNT(*)! Thanks. -----Original Message----- From: Rolando Edwards <redwa...@logicworks.net> Sent: Wednesday, August 05, 2009 23:12:09 Subject: RE: How to Detect MySql table update/difference I have good news and bad news for you when it comes to MySQL 5.x. Good News if you are counting against MyISAM Bad News if you are counting against InnoDB Good News --------- For MyISAM Just use either SELECT table_rows FROM information_schema.tables WHERE table_schema='<given db name>' and table_name='<given table name>'; Or SELECT COUNT(1) FROM <db-name>.<tbl-name>; (This will work in MySQL 4.x as well) Bad News -------- For InnoDB SELECT COUNT(1) FROM <db-name>.<tbl-name>, even though it can run faster than SELECT COUNT(*), will still count every row in the table anyway. If you are using InnoDB, you are on your own !!!! If you are using MyISAM, have fun !!!! Rolando A. Edwards MySQL DBA (CMDBA) 155 Avenue of the Americas, Fifth Floor New York, NY 10013 212-625-5307 (Work) 201-660-3221 (Cell) AIM & Skype : RolandoLogicWorx redwa...@logicworks.net -----Original Message----- From: BS TLC [mailto:bs...@ymail.com] Sent: Wednesday, August 05, 2009 10:30 AM To: mysql@lists.mysql.com Subject: How to Detect MySql table update/difference Hi, I'm a novel developer of MySql and now I am trying to create a mysql query to detect table updates. I query a database table every X seconds, and i want to get only the different rows in the table. The result that I want to have is simply TABLE (t = now) - TABLE (t = X second ago) Every time that i query the database I store the table situation in another table, called TABLE_TEMP, so the operation of difference detection is TABLE_DIFERENCE = TABLE - TABLE_TEMP. How can I do this query? The problem that I have is that I don't know the structure of the table and I want to create a program with can be used for all types of data and tables. Please help me. Best regards -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=redwa...@logicworks.net -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
