Thread

1. Bitwise operators in SQL

   Arcady Genkin <a.genkin@utoronto.ca> — 2001-05-25T16:17:19Z

   I'm writing SQL code for dynamic page generation in PHP.  I'd like to
   be able to determine whether a certain class of users has access to
   certain pages.  I was thinking of doing it the usual way: set
   bitmasks, e.g. STUDENT=1, INSTRUCTOR=2, STAFF=4, etc., and store
   permissions from bitwise AND of applicable masks in the table that
   keeps info about each page.  But the problem is that there are no
   bitwise operators among Postgres's supported operators.  So, I cannot
   write something like
   
   select name from pages where access&2>0;
   
   Is there a standard way to approach this kind of problem?
   
   Many thanks,
   -- 
   Arcady Genkin
   
   

2. Re: Bitwise operators in SQL

   Peter Eisentraut <peter_e@gmx.net> — 2001-05-25T18:12:22Z

   Arcady Genkin writes:
   
   > But the problem is that there are no
   > bitwise operators among Postgres's supported operators.  So, I cannot
   > write something like
   >
   > select name from pages where access&2>0;
   >
   > Is there a standard way to approach this kind of problem?
   
   Upgrading.
   
   -- 
   Peter Eisentraut   peter_e@gmx.net   http://funkturm.homeip.net/~peter
   
   
   

3. Re: Bitwise operators in SQL

   Arcady Genkin <a.genkin@utoronto.ca> — 2001-05-25T20:25:11Z

   Peter Eisentraut <peter_e@gmx.net> writes:
   
   > Arcady Genkin writes:
   > 
   > > But the problem is that there are no
   > > bitwise operators among Postgres's supported operators.  So, I cannot
   > > write something like
   > >
   > > select name from pages where access&2>0;
   > >
   > > Is there a standard way to approach this kind of problem?
   > 
   > Upgrading.
   
   Indeed, thanks.  I was reading the docs for 7.0, and didn't notice
   that 7.1 has bitwise operators.
   
   Thanks a lot,
   -- 
   Arcady Genkin