Re: constraint function, newbie

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Re: constraint function, newbie

От:
Lee Harr <missive@frontiernet.net>
Дата:
In article , Michal Adamczak:
> hi
> i am learning postgres and made a library model
> 
> i dont want a user to be able to borrow 2 items (copies)
> of the same book so made a function to check it (below)
> 
> the function works fine but now i would like to add a constraint,
> unfortunatelly i fail
> 
> here's my try:
> 
> create function bookborrow_check_insert
> (bookborrow.userid%TYPE, bookborrow.bookitem_id%TYPE) 
> returns bool as 
> 'select NOT $1 in (select userid from bookborrow where userid = $1 and
> bookitem_id = $2 and returned is null)'
>  language sql;
> 
>=> alter table bookborrow add check(bookborrow_check_insert\
 (userid, bookitem_id));
> ERROR:  AlterTableAddConstraint: rejected due to CHECK constraint 
> 
>=> alter table bookborrow add  constraint check_insert check(bookborrow_check_insert\
 (userid, bookitem_id));
> ERROR:  AlterTableAddConstraint: rejected due to CHECK constraint check_insert
> 


Is there data in the table?

Maybe try it on an empty copy of the database.

Re: constraint function, newbie

От:
"Michal Adamczak" <pokryfka@druid.if.uj.edu.pl>
Дата:
> Is there data in the table?
> 
> Maybe try it on an empty copy of the database.

that was the cause indeed, tnx

-- 
Michal Adamczak
pokryfka @ druid.if.uj.edu.pl
GS dpu C+++ UL+++++ L+++(++++) w--- !tv h*
I code AND I bathe. (seen on slashdot)
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