Thread: MySql Concat function equivalent

Is there any way to create a postgresql function that would take unlimited parameters like mysql's concat()? Currently my application was calling the concat function with parameters comming from php...something like "select concat(".implode(',',array)."). So without having a predefined number of parameters, I would need a function that could be able to concatenate the fields no matter how many they are. Is this possible?

Which version of PostgreSQL are you on?  If you're on >= 8.4 you can use these to simulate it:

CREATE FUNCTION concat(VARIADIC arr anyarray) RETURNS text AS $$
    SELECT array_to_string($1, '');
$$ LANGUAGE SQL;

CREATE FUNCTION concat_ws(delim text, VARIADIC arr anyarray) RETURNS text AS $$
    SELECT array_to_string($2, $1);
$$ LANGUAGE SQL;

Then you can run:

SELECT concat(1,2,3);

to get:

123

or:

SELECT concat_ws('-',1,2,3);

to get:

1-2-3

Note that all elements of the array you're passing in have to be the same type.  And 9.1 should have this a better version of this functionality built in: http://developer.postgresql.org/pgdocs/postgres/functions-string.html

Hope that helps.

--
Thom Brown
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