So we're talking apples to apples, and since you seem like a nice enough guy to keep around, when we request DDL and data we're looking for directly runnable data, not just a formatted set, like so:

CREATE TABLE #GPM

(PPMID VARCHAR(2) NOT NULL,--Record ID

PCMPNY NUMERIC( 2, 0) NOT NULL,-- Company Number

PYear Numeric( 4, 0) NOT NULL,-- Fiscal Year

Period NUMERIC( 2,0) NOT NULL,-- Fiscal Period

PStart NUMERIC(8,0) NOT NULL,-- Period Start Date

PEnd NUMERIC(8,0) NOT NULL-- Period End Date

)

INSERT INTO #GPM

SELECT'PM', 20, 2012, 1, 20120102, 20120129 UNION ALL

SELECT'PM', 20, 2012, 2, 20120130, 20120326

Now, to move past that. SQL Server has the DATETIME (and DATE) datatypes, and you'll find they're usually more effective for this than Numerics are. However, that said, you don't need an extra function for your dates, all you need is another column in your GPM table indicating the quarter. It'll repeat for the necessary rows the same way Fiscal Year would.

From there, you're looking at joining the dates from the table into the GPM table. Now, usually a range isn't the best of choices for direct joins like this but I'm not sure how much data you have coming off the primary table, and this table seems small enough that doing a between join shouldn't hurt you much. I'd avoid the function entirely and adjust the ranged calendar table you have here. I'd personally also switch PStart and PEnd into DATETIMEs.