We Heart Code » postgres

Postgres select replace with regular expression

Tim — Wed, 02 Jan 2008 21:22:50 +0000

Postgres seriously kicks ass, here's a quick way to do a substring based on a regular expression. A Co-worker wanted to get the first word out of a column that contained a sentence. If we were using something lame like oracle we'd have to do gymnastics to do that.

It's a one-liner in postgres.

SELECT substring('this is a sentence' FROM '^(.+?)\\s.+$')

So we're selecting out the group that is a series of characters at the start of a line (column) before a space. Epic win.

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Postgres Array Joins

jason — Wed, 25 Jul 2007 13:27:03 +0000

Every once in a while you'll come across the need to create a temp table to perform a complicated select query. Not being a big fan of creating these temp tables, I came up with a better solution. Leveraging Postgresql's array structure, I wrote a function that converts a varchar[] to a record set.

CREATE OR REPLACE FUNCTION array_to_rows( character varying[])
RETURNS SETOF character varying AS
$BODY$
DECLARE
in_array alias FOR $1;

out_varchar varchar;
BEGIN
FOR i IN 1..array_upper(in_array,1) loop
RETURN next in_array[i];
end loop;

RETURN;
END
$BODY$
LANGUAGE 'plpgsql' STABLE;

This allows me to pass in an unknown amount of data and perform a LEFT OUTER JOIN on it without losing my orignal data.

SELECT

a.name, b.name, b.other_info

FROM

(SELECT array_to_rows AS name FROM array_to_rows(ARRAY['JOE', 'SCOTT', 'BOB']) a

LEFT OUTER JOIN names b ON a.name ilike '%' || b.name || '%'

Hope you find this useful!

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Formatting Numbers in Oracle and Postgres

Tim — Mon, 09 Oct 2006 12:29:06 +0000

When dealing with large numbers in oracle sometimes it can be hard to read the results from a query with no formatting in the results. I know I have misread numbers from a query many times. Well, I finally got around to looking up how to format numbers in oracle. And who knew -- TO_CHAR does it for us.

Example In Oracle:

SELECT to_char(5689731,'$9,999,999.00') AS mysalary FROM DUAL

Jason says this also works in Postgres!
Example in Postgres:

SELECT to_char(5689731, '$9,999,999.00') AS mysalary

returns

$5,689,731.00

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