I agree that there are better ways to do this.
But for me this works. (legacy driven situation)

INSERT INTO tbinitialisatie (col1, col2)
 SELECT 'x', 'y'
 FROM tbinitialisatie
 WHERE not exists (select * from tbinitialisatie where col1 = 'x' and col2 = 'y')
 LIMIT 1


Pau Marc Muñoz Torres schreef:
Ok , thanks Sim, now i see it

P

2011/9/5 Sim Zacks <sim@compulab.co.il>
On 09/05/2011 01:37 PM, Pau Marc Muñoz Torres wrote:
i don't  see it clear, let me put an example

i got the following table

molec varchar(30)
seq varchar(100)

where I insert my values

 lets image that i have a record introduced as ('ubq', 'aadgylpittrs')

how i can prevent to insert another record where molec='ubq' ?

thanks

Either put a unique constraint on molec or do
insert into tbl(molec,seq)
select 'ubq', 'aadgylpittrs' where not exists(select molec from tbl where molec='ubq')



--
Pau Marc Muñoz Torres

Laboratori de Biologia Computacional  
Institut de  Biotecnologia   i Biomedicina Vicent Villar                                   
Universitat Autonoma de Barcelona
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telèfon:  (+34)935 86 89 39
Email : paumarc.munoz@bioinf.uab.cat