Using Ruby & ADO to Work with MS Access Databases

A reader in the Ruby forum recently asked about using Ruby to get data from a Microsoft Access database. This can be done easily using the ActiveX Data Objects (ADO), via the win32ole library. Let's walk through it...

As usual, require the win32ole library:

require 'win32ole'

Next, create a new ADODB Connection object, which will manage the connection to the database:

connection = WIN32OLE.new('ADODB.Connection')

To open a connection to the Access database, call the Connection object's Open method, passing it the Provider and Data Source (your Access mdb file) parameters:

connection.Open('Provider=Microsoft.Jet.OLEDB.4.0;
                 Data Source=c:\baseball\lahman54.mdb')

To execute an SQL statement that does not return a recordset (ie, CREATE, ALTER, INSERT), you can call the Connection object's Execute method:

connection.Execute("INSERT INTO HallOfFame VALUES ('Dave', 'Concepcion');")

To perform a query that returns a recordset of data, first create a new ADODB Recordset object:

recordset = WIN32OLE.new('ADODB.Recordset')

Then call the Recordset object's Open method, passing it the SQL statement and your existing Connection object:

recordset.Open(sql, connection)

This loads the query results into the Recordset object. The Recordset object's GetRows method returns an array of columns (not rows, as you might expect), so we'll use the Ruby array's transpose method to convert it to an array of rows:

data = recordset.GetRows.transpose

Close the Connection object by calling its Close method:

recordset.Close

We could create a simple class to wrap up this functionality:

class AccessDb
    attr_accessor :mdb, :connection, :data, :fields

    def initialize(mdb=nil)
        @mdb = mdb
        @connection = nil
        @data = nil
        @fields = nil
    end

    def open
        connection_string =  'Provider=Microsoft.Jet.OLEDB.4.0;Data Source='
        connection_string << @mdb
        @connection = WIN32OLE.new('ADODB.Connection')
        @connection.Open(connection_string)
    end

    def query(sql)
        recordset = WIN32OLE.new('ADODB.Recordset')
        recordset.Open(sql, @connection)
        @fields = []
        recordset.Fields.each do |field|
            @fields << field.Name
        end
        begin
            @data = recordset.GetRows.transpose
        rescue
            @data = []
        end
        recordset.Close
    end

    def execute(sql)
        @connection.Execute(sql)
    end

    def close
        @connection.Close
    end
end

This class is very similar to an SqlServer class I previously discussed.
We would use this AccessDb class as follows:

db = AccessDb.new('c:\Baseball\lahman54.mdb')
db.open

db.query("SELECT * FROM AllStar WHERE playerID = 'conceda01';")
field_names = db.fields
rows = db.data

db.execute("INSERT INTO HallOfFame VALUES ('Dave', 'Concepcion');")

db.close

That about wraps up our show for today. As always, feel free to post a comment here or email me with questions, comments, or suggestions.

Thanks for stopping by!