How to draw a name in a database

Question

I have names in my database and I want to draw a name for a contest.

Anyone have an idea for that ?

Thanks !!

[what have you tried?](http://mattgemmell.com/2008/12/08/what-have-you-tried/) — Songo, May 07 '12 at 09:03

score 2 · Answer 1 · answered May 07 '12 at 08:58

2

A query like this could work

SELECT * FROM `table` WHERE id >= (SELECT FLOOR( MAX(id) * RAND()) FROM `table` ) ORDER BY id LIMIT 1;

answered May 07 '12 at 08:58

heldt

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score 2 · Accepted Answer · answered May 07 '12 at 08:59

2

SELECT * FROM table WHERE num_value >= RAND() * (SELECT MAX(num_value) FROM table) LIMIT 1

This works in constant time, regardless of the table size, if num_value is indexed. One caveat: this assumes that num_value is equally distributed in the range 0..MAX(num_value). If your dataset strongly deviates from this assumption, you will get skewed results (some rows will appear more often than others).

answered May 07 '12 at 08:59

NullPoiиteя

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Thanks, it's exactly what I needed ! I tried to do that in pure php, but your idea is much better ! – Sarah L. May 07 '12 at 09:08

How to draw a name in a database

2 Answers2