Postgres implements function generate_series, a function that returns a table of a set of integers. Unfortunately, MySQL lacks this function and Redshifts implementation is pretty useless (It only works on the leader node?? Really?).

In a combination with a CROSS JOIN, number tables are often used to build map tables, from attributes stored in lists in strings. They are also used to build date table (see below).

I’ve seen a few implementations of numeric series generating SELECT statements, but they are usually more complex and larger than this one.

The SQL code makes a bunch of two row tables and cross joins them, using them as binary counters. The code will generate all the numbers between 0 and 255 (2^8-1)

```
SELECT
p0.n
+ p1.n*2
+ p2.n * POWER(2,2)
+ p3.n * POWER(2,3)
+ p4.n * POWER(2,4)
+ p5.n * POWER(2,5)
+ p6.n * POWER(2,6)
+ p7.n * POWER(2,7)
as number
FROM
(SELECT 0 as n UNION SELECT 1) p0,
(SELECT 0 as n UNION SELECT 1) p1,
(SELECT 0 as n UNION SELECT 1) p2,
(SELECT 0 as n UNION SELECT 1) p3,
(SELECT 0 as n UNION SELECT 1) p4,
(SELECT 0 as n UNION SELECT 1) p5,
(SELECT 0 as n UNION SELECT 1) p6,
(SELECT 0 as n UNION SELECT 1) p7
```

Its pretty easy to create a derived table for general use. **Play with this Code on Learn.looker.com**

```
- view: numbers
derived_table:
persist_for: 5 hours
indexes: [number]
sql: |
SELECT
p0.n
+ p1.n*2
+ p2.n * POWER(2,2)
+ p3.n * POWER(2,3)
+ p4.n * POWER(2,4)
+ p5.n * POWER(2,5)
+ p6.n * POWER(2,6)
+ p7.n * POWER(2,7)
as number
FROM
(SELECT 0 as n UNION SELECT 1) p0,
(SELECT 0 as n UNION SELECT 1) p1,
(SELECT 0 as n UNION SELECT 1) p2,
(SELECT 0 as n UNION SELECT 1) p3,
(SELECT 0 as n UNION SELECT 1) p4,
(SELECT 0 as n UNION SELECT 1) p5,
(SELECT 0 as n UNION SELECT 1) p6,
(SELECT 0 as n UNION SELECT 1) p7
fields:
- dimension: number
type: number
```

Another useful form of this table is to generate dates.

```
- view: dates
derived_table:
persist_for: 5 hours
indexes: [series_date]
sql: |
SELECT
DATE_ADD('2001-01-01', INTERVAL numbers.number DAY)
as series_date
FROM ${numbers.SQL_TABLE_NAME} AS numbers
fields:
- dimension: series_date
type: date
```