How to join three tables

[#1]

I have three tables:

Release Date

technology_id	release_date
1	01/01/2010

Support End Date

technology_id	end_date
1	31/01/2011

Extended Support End Date

technology_id	extended_end_date
1	31/01/2012

Instead of having three tables i want to have it in following form:

technology_id	start_date	end_date	period
id	release_date	end_date	Mainstream Support
id	end_date	extended_end_date	Extended Support

'period' column and its values needs to be set explicitly(i do not have this in any tables).

For Example:

technology_id	start_date	end_date	period
1	01/01/2010	31/01/2011	Mainstream Support
1	31/01/2011	31/01/2012	Extended Support

I want to use this for creating gantt chart (using bar graph). I'm not able to figure out how to combine the table in above format.

Need help to figure this out please.