Re: About union sql Mysql 4.x

[Gleb Paharenko <suppressed>]

Hello.

If you want all records with item=1 to be at the beginning and
sorted in a random order you can use this query:

select * from tablea order by if(item=1,0,1),  rand();


HALIL DEMIREZEN wrote:
> What if i want to list all the records not limiting them to a constant?
> 
> 
> 
> ------------------------------------------------------------
> Halil Demirezen 
> System Support Engineer/ Sistem Destek Muhendisi 
> Mobile Tel/Cep Tel: +90(543) 502 04 42
> E-Mail/E-Posta: suppressed
> -----------------------------------------------------------
> 
> 
> 
> 
> Gleb Paharenko <suppressed> 
> 05.12.2005 12:19
> 
> To
> suppressed
> cc
> 
> Subject
> Re: About union sql  Mysql 4.x
> 
> 
> 
> 
> 
> 
> Hello.
> 
> 
> 
> From http://dev.mysql.com/doc/refman/5.0/en/union.html:
> 
> 
> 
> "ORDER BY for individual SELECT statements within parentheses has an
> 
> effect only when combined with LIMIT. Otherwise, the ORDER BY is
> 
> optimized away."
> 
> 
> 
> 
> 
> Therefore you're getting the same results, because ORDER BY doen't
> 
> work for your query.
> 
> 
> 
> 
> 
> 
> 
> HALIL DEMIREZEN wrote:
> 
> 
>>Hi,
> 
> 
> 
>>I am trying to run an sql query such as below to list items=x randomly 
> 
> and 
> 
> 
>>then items != x randomly.. 
> 
> 
> 
> 
>>mysql> (select * from tablea where item=1 order by rand()) union all 
> 
> 
>>(select  * from tablea where item != 1 order by rand());
> 
> 
> 
>>but the result is not as expected. rand() seems not to be working...
> 
> 
> 
>>What can be the problem? or what can be the difference between my will 
> 
> and 
> 
> 
>>the exact result of the query?
> 
> 
> 
>>Thanks..
> 
> 
> 
> 
>>------------------------------------------------------------
> 
> 
>>Halil Demirezen 
> 
> 
>>System Support Engineer/ Sistem Destek Muhendisi 
> 
> 
>>Mobile Tel/Cep Tel: +90(543) 502 04 42
> 
> 
>>E-Mail/E-Posta: suppressed
> 
> 
>>-----------------------------------------------------------
> 
> 
> 
> 
> 


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