From: khaines@...
Date: 2006-12-06T10:18:54+09:00
Subject: Re: Lisp comprehensions => SQL

On Wed, 6 Dec 2006, Victor "Zverok" Shepelev wrote:

> #having
> employees.select do |e|
>   sort_by(e.age)
>   limit(2,10)
>   (e.name == 'John') & (e.salary > 50)
> end
>
> #proposal:
>
> employees.select{|e| (e.name == 'John') & (e.salary > 50)}.sort_by{|e|
> e.age}[2..10]
>
> The latter is "just Ruby".
>

Actually, you could do that second one with Kansas.  With the current 
Kansas, it'd be:

dbh.select(:Employees) {|e| (e.name == 'John') & (e.salary > 
50)}.sort_by{|e| e.age}[2..10]

The difference, though, is that it won't do all of that on the database.

The database will do "select * from employees where e.name = 'John' and 
e.salary > 50" and then the results will be sorted by Ruby and the set 
extracted by Ruby.


Kirk Haines