SELECT range of integers in MySQL. Eg. 1,2,3,4,...,n;

I need开发者_运维技巧 to select range of integer in MySQL. Something like this

SELECT RANGE(10,20) AS range;

returns

10, 11, 12, 13, 14, ..., 20

Why?

I would like to select random phone number from range which is not yet registered. This is idea.

SELECT RANGE(100000,999999) AS range FROM phone WHERE phoneNum <> range LIMIT FLOOR(100000 + RAND()*(899999);

Problems with your query:

1. You can't use range in the WHERE clause. It is an alias and will only be defined after the WHERE clause is performed.
2. Even if you could use it, it makes no sense to compare a number with a set of numbers using <>. In general you could use IN(...), but in you particular case you should use BETWEEN 100000 and 999999 and avoid the need for a RANGE function.
3. If you only want one number then the limit should be 1, not something random. Usually to select random items you use ORDER BY RAND().

Try using this query:

SELECT phoneNum, 100000 as rangeStart, 999999 AS rangeEnd
FROM phone
WHERE phoneNum NOT BETWEEN 100000 AND 999999
ORDER BY RAND()
LIMIT 1

If you want to find a number not in your table and the available numbers are not close to depletion (say less than 80% are assigned) a good approach would be to generate random numbers and check if they are assigned until you find one that isn't.

A pure MySQL solution may exists but I think it needs some twisted joins, random and modulus.

An alternative:

First of all create a table with just numbers that has all the numbers from 1 to MAX_NUM.

Then use this query:

SELECT n.id as newNumber
FROM numbers AS n
LEFT JOIN phone AS p
    ON p.phoneNum = n.id
WHERE 
    p.phoneNum IS NULL AND
    n.id BETWEEN lowerLimit AND upperLIMIT    
ORDER BY RAND()
LIMIT 1

This way you can also get multiple number relatively fast by changing the limit value.

Currently the MariaDB SEQUENCE engine can do this for you:

SELECT `seq` FROM `seq_1234_to_5678`;