SQL LIKE condition to check for integer?

Question

I am using a set of SQL LIKE conditions to go through the alphabet and list all items beginning with the appropriate letter, e.g. to get all books where the title starts wit

Answer 1

Which one of those is indexable?

This one is definitely btree-indexable:

WHERE title >= '0' AND title < ':'

Note that ':' comes after '9' in ASCII.

Answer 2

That will select (by a regex) every book which has a title starting with a number, is that what you want?

SELECT * FROM books WHERE title ~ '^[0-9]'

if you want integers which start with specific digits, you could use:

SELECT * FROM books WHERE CAST(price AS TEXT) LIKE '123%'

or use (if all your numbers have the same number of digits (a constraint would be useful then))

SELECT * FROM books WHERE price BETWEEN 123000 AND 123999;

Answer 3

Assuming that you're looking for "numbers that start with 7" rather than "strings that start with 7," maybe something like

select * from books where convert(char(32), book_id) like '7%'

Or whatever the Postgres equivalent of convert is.

Answer 4

I'm late to the party here, but if you're dealing with integers of a fixed length you can just do integer comparison:

SELECT * FROM books WHERE price > 89999 AND price < 90100;

Answer 5

If you want to search as string, you can cast to text like this:

SELECT * FROM books WHERE price::TEXT LIKE '123%'

Answer 6

Tested on PostgreSQL 9.5 :

-- only digits

select * from books where title ~ '^[0-9]*$';

or,

select * from books where title SIMILAR TO '[0-9]*';

-- start with digit

select * from books where title ~ '^[0-9]+';