Originally posted here.

Numbers tables are truly invaluable. I use them all of the time for string manipulation, simulating window functions, populating test tables with lots of data, eliminating cursor logic, and many other tasks that would be incredibly difficult without them.

Is using a table of numbers a hack, as I've seen some people claim? No. Show me another way to efficiently do all of the things a numbers table can. Does it waste space? No. The script below will use up around 900 KB of disk space in each database. That's absolutely nothing. You'll end up getting millions, maybe billions of times the disk space investment back in terms of ease of development and time saved.

So henceforth, I will assume in this blog that everyone reading has a Numbers table. And I will politely link to this article as a gentle reminder. But I want you to open Query Analyzer right now and use the following script:

USE Model
GO

CREATE TABLE Numbers
(
	Number INT NOT NULL,
	CONSTRAINT PK_Numbers 
		PRIMARY KEY CLUSTERED (Number)
		WITH FILLFACTOR = 100
)

INSERT INTO Numbers
SELECT
	(a.Number * 256) + b.Number AS Number
FROM 
	(
		SELECT number
		FROM master..spt_values
		WHERE 
			type = 'P'
			AND number <= 255
	) a (Number),
	(
		SELECT number
		FROM master..spt_values
		WHERE 
			type = 'P'
			AND number <= 255
	) b (Number)
GO

There. Now you automatically have a Numbers table in every database you create, populated with every number between 0 and 65535. That's big enough for most tasks. If you need more numbers, just insert more! It's fun and easy! And trust me, you'll use this table. A lot. And you'll thank me one day, probably by sending me lots of gifts, as a very small token of your appreciation.

But in the meantime, here are two links with more information on using a numbers table:

ASP FAQ #2516, "Why should I consider using an auxiliary numbers table?"

Fun with numbers in Transact-SQL queries