declare @x table (product varchar(10), fromdate date, todate date) -- forecast declare @y table (product varchar(10), fromdate date, todate date) -- purchases declare @z table (id int identity(1,1), product varchar(10), fromdate date, todate date) -- result insert @x values ('lrecs', '20150101', '20161231') insert @x values ('srecs', '20150701', '20161231') insert @y values ('lrecs', '20150401', '20150630') insert @y values ('lrecs', '20160101', '20160630') insert @y values ('srecs', '20160101', '20161231') /* product fromdate todate ------------------------------ lrecs 2015-01-01 2015-03-31 lrecs 2015-04-01 2015-06-30 lrecs 2015-07-01 2015-12-31 lrecs 2016-01-01 2016-06-30 lrecs 2016-07-01 2016-12-31 srecs 2015-07-01 2015-12-31 srecs 2016-01-01 2016-12-31 */