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Need help setting up an ORDER BY


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#1 Hostile

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Posted 22 September 2010 - 07:04 PM

I'm trying to take somebody else's code who used to work my job but is gone and add a sort order. Right now it's ascending by date. I need it to descend.

$Query='select * from '.$Category.' where isAvailable<>""';

Normally this would be done by adding this
SELECT * FROM table_name
ORDER BY Date DESC

I tried this but it didn't work.
$Query='select * from '.$Category.' ORDER BY Date DESC where isAvailable<>""';

I know it's something simple as I'm not the best coder around. Any help will do.

#2 Beowulf

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Posted 23 September 2010 - 03:22 AM

The WHERE clause has to precede the ORDER BY. In short, move the ORDER BY to the end of the statement.

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#3 Bart

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Posted 23 September 2010 - 02:37 PM

As a general rule, clauses in the query must be given in the order they will be executed (SELECT is an exception), so:

- You need to filter the result before you can sort it -> WHERE comes before ORDER
- Grouping must be done after filtering -> WHERE comes before GROUP BY
- HAVING lets you add another filter after grouping has been done -> HAVING comes after GROUP BY
- Only after you've filtered, grouped and whatnot can you determine what the first X rows are -> LIMIT comes last
- etc...
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#4 Jeeves

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Posted 26 September 2010 - 05:00 AM

Or WOGHL for short, which doesn't make it any easier to remember :p
Also, if you have access to phpMyAdmin, use it. Echo your query to check the variables are appearing right, then copy-paste to phpMyAdmin's query box and you can easily see any errors and try changes faster than through editing the PHP.

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