Rob Gould wrote:
I'm not sure if I need to write a PHP for-loop to do this, or if it can all be done in one SQL statement? Basically, I want to copy all the barcodes from one table and put them into another table, but only if the barcode in the first table > 0, and only if the wineid's match from table to table. Steps individually are something like this: 1) First, I get all the records from the "wine" table that have barcodes, like this: SELECT * FROM `wine` WHERE barcode2 > 0 The fields I need are "barcode2", and "wineid" 2) Next, I need to match all the wineid's from this "wine" table with the wine id's from the "usersdata" table. Both fields in both tables are called "wineid". 3) Then, if the wineid's match, I need to copy the "barcode2" value from the wine table and put it into the field "custombarcode" in the "usersdata" table. I'm tempted to write a PHP script which does a while-loop through all the records returned from the wine table and do the matching with the usersdata table, but I wouldn't be surprised if there's some sort of table-join-type query that can do all this in one step.
Looks like you should be able to do this in the SQL. Creating a dummy DB and testing, the following seems to do the trick.
UPDATE usersdata SET custombarcode = ( SELECT barcode2 FROM wine WHERE usersdata.wineid = wine.wineid AND wine.barcode2 > 0 ) Here is the DB schema and data that I used for the test CREATE TABLE IF NOT EXISTS `usersdata` ( `id` int(11) NOT NULL auto_increment, `wineid` int(11) NOT NULL, `custombarcode` int(11) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_bin AUTO_INCREMENT=7 ; INSERT INTO `usersdata` (`id`, `wineid`, `custombarcode`) VALUES (1, 1, 0), (2, 2, 0), (3, 3, 0), (4, 4, 0), (5, 1, 0), (6, 1, 0); CREATE TABLE IF NOT EXISTS `wine` ( `wineid` int(11) NOT NULL auto_increment, `barcode2` int(11) NOT NULL, PRIMARY KEY (`wineid`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_bin AUTO_INCREMENT=4 ; INSERT INTO `wine` (`wineid`, `barcode2`) VALUES (1, 5), (2, -5), (3, 10); -- Jim Lucas A: Maybe because some people are too annoyed by top-posting. Q: Why do I not get an answer to my question(s)? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
