How to parse a SQL result and convert it to Ruby hash - sql

Question

I want to convert a SQL query result into a Ruby hash, where only two rows are shown and the first act as key and second as value. For example, if my query got this result:
+----+--------+
| id | name |
+--- +--------+
| 1 | a |
| 2 | b |
| 3 | c |
| 4 | d |
| 5 | e |
+----+--------+
I want to manipulate this data to get a Ruby hash like this:
h = { '1' => 'a',
'2' => 'b'.
'3' => 'c',
'4' => 'd',
'5' => 'e' }
How can I get this done?

Answer 1

I use ruby Sequel in most of my non-rails projects. It's an excellent ORM for SQL databases.
Here is a code sample using SQLite (in memory):
#!/usr/bin/env ruby
require 'sequel'
# create db in memory
DB = Sequel.sqlite
# create table
DB.create_table :items do
primary_key :id
String :name
end
# Create a dataset
items = DB[:items]
# Populate the table
items.insert(:name => 'john')
items.insert(:name => 'mike')
items.insert(:name => 'nick')
puts "#{items.all}"
# => [{:id=>1, :name=>"john"}, {:id=>2, :name=>"mike"}, {:id=>3, :name=>"nick"}]
# initialize hash object
h = {}
# Create the hash in the form you want
items.all.each do |entry|
h[entry[:id]]= entry[:name]
end
# p the hash
p h # => {1=>"john", 2=>"mike", 3=>"nick"}
NOTE: Sequel is extremely powerful. There might be a method to do what you what you want directly, without passing the data through the loop. However, you'll have to read the documentation to find out if you need to clean your code.
Hope this helps!
UPDATE: So here is the updated code after Jeremy Evan's (author of Sequel):
#!/usr/bin/env ruby
require 'sequel'
# create db in memory
DB = Sequel.sqlite
# create table
DB.create_table :items do
primary_key :id
String :name
end
# Create a dataset
items = DB[:items]
# Populate the table
items.insert(:name => 'john')
items.insert(:name => 'mike')
items.insert(:name => 'nick')
# Return hash of items
p items.select_hash(:id, :name) # => {1=>"john", 2=>"mike", 3=>"nick"}