[php] mysql> zufallszahl?

[Kai Meder]

MK> hi.
Nabend Matthias,

MK> gibt es unter bei mysql eine funktion, die eine zufallszahl erzeugt?
kloar

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RAND()
RAND(N) 
Returns a random floating-point value in the range 0 to 1.0.
If an integer argument N is specified, it is used as the seed value:

mysql> select RAND();
        -> 0.5925
mysql> select RAND(20);
        -> 0.1811
mysql> select RAND(20);
        -> 0.1811
mysql> select RAND();
        -> 0.2079
mysql> select RAND();
        -> 0.7888

You can't use a column with RAND() values in an ORDER BY clause,
because ORDER BY would evaluate the column multiple times.
In MySQL Version 3.23, you can, however,
do: SELECT * FROM table_name ORDER BY RAND()
This is useful to get a random sample of a set
SELECT * FROM table1,table2 WHERE a=b AND c<d ORDER BY RAND() LIMIT 1000.
Note that a RAND() in a WHERE clause will be
re-evaluated every time the WHERE is executed.
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=> http://www.mysql.com/doc/M/a/Mathematical_functions.html

mfg
kai

-- 
Kai Meder
www.cn-media.de
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