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')