The generate_series Table-Valued Function

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The generate_series Table-Valued Function

# 1. Overview

The generate_series(START,END,STEP) table-valued function is a loadable extension included in the SQLite source tree, and compiled into the command-line shell. The generate_series() table has a single result column named "value" holding integer values and a number of rows determined by the parameters START, END, and STEP. The first row of the table has a value of START. Subsequent rows increase by STEP up to END.

Omitted parameters take on default values. STEP defaults to 1. END defaults to 9223372036854775807. START defaults to 0.

## 1.1. Equivalent Recursive Common Table Expression

The generate_series table can be simulated using a recursive common table expression. If the three parameters are $start, $end, and $step, then the equivalent common table expression is:

    WITH RECURSIVE generate_series(value) AS (
      SELECT $start
      UNION ALL
      SELECT value+$step FROM generate_series
       WHERE value+$step<=$end
    ) ...

The common table expression works without having to load an extension. On the other hand, the extension is easier to program and faster.

# 2. Usage Examples

Generate all multiples of 5 less than or equal to 100:

    SELECT value FROM generate_series(5,100,5);

Generate the 20 random integer values:

    SELECT random() FROM generate_series LIMIT 20;

Find the name of every customer whose account number is an even multiple of 100 between 10000 and 20000.

    SELECT customer.name
      FROM customer, generate_series(10000,20000,100)
     WHERE customer.id=value;
    /* or */
    SELECT name FROM customer
     WHERE id IN (SELECT value
                    FROM generate_series(10000,20000,200));