To: pgsql-admin@postgresql.org
From: Thomas Kellerer <spam_eater@gmx.net>
Subject: Re: need help to write a function in postgresql
Date: Thu, 19 Jul 2012 12:28:03 +0200
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In-Reply-To: <000b01cd658e$e66ae920$b340bb60$@avineonindia.com>

Madhu.Lanka, 19.07.2012 11:14:
> Hi Friends
>
> Can u please help to write a function for the following scenario?
>
> I have 3 table’s user_roles, principals and roles.
>
> I have to write a function in postgresql which should excepts 2 parameters (name, password)
>
> With those 2 parameters the query should be executed and return the result.(Result of the query will be 1 or more rows).
>
> The query is working fine if executed it manually by hardcoding the values for name and password, but is as to be written in function so that I can send different values.
>
> “select u.role_id,u.user_id,p.name,p.creation_date,p.telephone_number,p.email,p.remarks,p.city,p.state,p.country,p.postal_address,p.company_name,p.department_name,p.contact_person,
>
> p.role_group,p.role_description,p.first_name,p.last_name,p.pincode,p.status,p.department_id,p.designation_id,r.role_name,r.right_edit,r.right_filter,r.right_search,r.right_browse,
>
> r.right_print, r.right_download,r.right_admin_user,r.right_image_creator,r.right_vector_download,r.right_wps,r.right_queries_filter,r.right_google_map,r.right_user_management,
>
> r.right_route_analysis, r.right_legend,r.right_treeview,r.insert,r.update,r.delete,r.query,r.lock from user_roles u,.principals p,roles r where p.PRINCIPAL_ID = u.USER_ID and
>
> r.role_id = u.role_id and p.name=? and p.password=?”
>

Something like this:

     create or replace function retrieve_user(uname text, pwd text)
       returns table (role_id integer, user_id integer, name text, .... more columns ...)
     as
     $$
     SELECT u.role_id,
            u.user_id,
            p.name,
            p.creation_date,
            p.telephone_number,
            .... more columns ...
     FROM user_roles u,
          principals p,
          roles r
     WHERE p.principal_id = u.user_id
     AND   r.role_id = u.role_id
     AND   p.name = $1
     AND   p.password = $2
     $$
     language SQL;


Then you can do:
     
     select *
     from retrieve_user('foo', 'bar');

Personally I'd prefer to create view that wraps that select statement and then simply do a

    select *
    from user_view
    where name = 'foo'
    and password = 'bar'

Regards
Thomas