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
FROMwine
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?
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