This document discusses connecting to different database systems like MySQL, Oracle, PostgreSQL, and SQLite using DataObjects and retrieving data using commands. It demonstrates how to execute queries, retrieve result sets and field values, and handle data typecasting between the database and Ruby types. It also mentions implementing specs to test the database adapters according to standard specifications and supporting the BigDecimal type.

1. DataObjects

2. Dirkjan Bussink

15. © Jon Truran

17. Text
Sorry for the photoshop skills...

18. connection = Mysql.real_connect(quot;localhostquot;, quot;rootquot;, quot;quot;, quot;do_testquot;)
reader = connection.query(quot;SELECT login, password FROM usersquot;)
reader.each do |row|
row[0] => 'dbussink'
row[1] => 'secret'
end
connection = OCI8.new(quot;rootquot;, quot;quot;, quot;localhostquot;)
reader = connection.exec(quot;SELECT login, password FROM usersquot;)
while row = reader.fetch
row[0] => 'dbussink'
row[1] => 'secret'
end
connection = PGconn.connect(quot;localhostquot;, 5432, nil, nil, quot;do_testquot;, quot;rootquot;, quot;quot;)
reader = connection.exec(quot;SELECT login, password FROM usersquot;)
for i in 0...reader.ntuples do
reader.getvalue(i,0) => 'dbussink'
reader.getvalue(i,1) => 'secret'
end
connection = SQLite3::Database.new(quot;do_test.dbquot;)
reader = connection.execute(quot;SELECT login, password FROM usersquot;)
reader[0][0] => 'dbussink'
reader[0][1] => 'secret'

19. It’s all about the API

20. connection = DataObjects::Connection.new(quot;mysql://root@localhost/do_testquot;)
command = connection.create_command(quot;INSERT INTO users (login) VALUES ('dbussink')quot;)
result = command.execute_non_query
result.affected_rows => 1
result.insert_id => 2

21. connection = DataObjects::Connection.new(quot;mysql://root@localhost/do_testquot;)
command = connection.create_command(quot;SELECT id, login, created_at FROM usersquot;)
reader = command.execute_reader
reader.fields => ['id', 'login', 'created_at']
while reader.next!
reader.values => [1, 'dbussink', Date.civil(2009, 5, 10)]
end

22. Typecasting

23. connection = DataObjects::Connection.new(quot;mysql://root@localhost/do_testquot;)
command = connection.create_command(quot;SELECT id, login, created_at FROM usersquot;)
command.set_types(String, String, String)
reader = command.execute_reader
reader.fields => ['id', 'login', 'created_at']
while reader.next!
reader.values => ['1', 'dbussink', '2009-5-10']
end

24. connection = DataObjects::Connection.new(quot;mysql://root@localhost/do_testquot;)
command = connection.create_command(quot;SELECT id, login, password FROM users WHERE login = ?quot;)
reader = command.execute_reader('dbussink')
reader.fields => ['id', 'login', 'created_at']
while reader.next!
reader.values => [1, 'dbussink', Date.civil(2009, 5, 10)]
end

25. Float
String
Integer
Date
BigDecimal
TrueClass
DateTime

26. Shared specs

27. describe DataObjects::Postgres::Command do
it_should_behave_like 'a Command'
it_should_behave_like 'a Command with async'
end

28. Implement standard
Command API
describe DataObjects::Postgres::Command do
it_should_behave_like 'a Command'
it_should_behave_like 'a Command with async'
end

29. Implement standard
Command API
describe DataObjects::Postgres::Command do
it_should_behave_like 'a Command'
it_should_behave_like 'a Command with async'
end
Command is green
thread friendly

30. describe 'DataObjects::Postgres with BigDecimal' do
it_should_behave_like 'supporting BigDecimal'
it_should_behave_like 'supporting BigDecimal autocasting'
end

31. Deserialize and
serialize BigDecimal
describe 'DataObjects::Postgres with BigDecimal' do
it_should_behave_like 'supporting BigDecimal'
it_should_behave_like 'supporting BigDecimal autocasting'
end

32. Deserialize and
serialize BigDecimal
describe 'DataObjects::Postgres with BigDecimal' do
it_should_behave_like 'supporting BigDecimal'
it_should_behave_like 'supporting BigDecimal autocasting'
end
Database provides
a mapped type (DECIMAL)

34. How can I help?

35. Improved transactions

36. Prepared statements

37. Specs!
And documentation too :)

38. ActiveRecord adapter