AquilaX's development blog » MySql

Randomize timestamp in MySQL

AquilaX — Mon, 16 Feb 2009 20:09:11 +0000

To randomize timestamp column in mysql You can use the following statement:

 
UPDATE your_table SET
timestamp_field = TIMESTAMPADD(MINUTE, RAND()*60,timestamp_field);

MySQL Database Alias

AquilaX — Fri, 07 Nov 2008 15:11:19 +0000

Sure, it's not possible to create alias for database in MySQL but here's a good workaround.
Don't forget to set the perditions for the alias as well.

MySQL UNION DISTINCT with result priority

AquilaX — Thu, 31 Jul 2008 11:47:16 +0000

I had to modify the search algorithm today, the idea was to fetch the exact matches first then the split words matches. The status quo was:

 
(SELECT product_id FROM products WHERE a=1)
  UNION DISTINCT
(SELECT product_id FROM products WHERE a=2 OR a=1)

I wanted to be sure that the result from the first sub-query are before the second one. The first thing that kame to my mind was:

 
(SELECT product_id, 1 as priority FROM products WHERE a=1)
  UNION DISTINCT
(SELECT product_id, 2 as priority FROM products WHERE a=2 OR a=1)
ORDER BY priority

but unfortunately this breaks the UNION DISTINCT clause and the results are duplicated.

I came out with the following solution:

 
SELECT MIN(priority) AS priority, product_id
FROM (
  (SELECT product_id, 5 AS priority FROM products WHERE a=1)
    UNION
  (SELECT product_id, 6 AS priority FROM products WHERE a=1 OR a=2)
) AS t
GROUP BY (product_id)
ORDER BY priority

Tags database schemas

AquilaX — Tue, 01 Apr 2008 10:53:06 +0000

A great article about tags database schemas can be found here.

phpMyAdmin change session expire time

AquilaX — Tue, 20 Nov 2007 09:17:37 +0000

To change phpMyAdmin's default session expire time (1800 s), change the 'LoginCookieValidity' setting to whatever value of seconds You like.
From the phpMyAdmin's wiki's Config page.

LoginCookieValidity
Define how long (in seconds) a login cookie is valid.
$cfg['LoginCookieValidity'] = 1800;
Maximum value is 2^31-1 , which is around 2.1 * 10^9. This is about 58 years.
If you are on a 64-bit system it is even longer. 2^63-1. Longer than the age of the universe.