jakub.vrbas wrote
> The following bug has been logged on the website:
>
> Bug reference: 10889
> Logged by: Jakub Vrbas
> Email address:
> jakub.vrbas@
> PostgreSQL version: 9.1.13
> Operating system: Debian
> Description:
>
> I have test_column (of type character varying). If I parse a float by
> regular expression, it isn't possible to add it to another float from
> regular expression.
>
> Example:
>
> SELECT
> (regexp_matches(test_column, '([0-9\.]*)'))[1]::float
> +
> (regexp_matches(test_column, '([0-9\.]*)'))[1]::float
> FROM test_table
>
> Results in "ERROR: functions and operators can take at most one set
> argument"
>
> Example 2 is OK:
> SELECT
> float_column
> +
> float_column
> FROM (
> SELECT
> (regexp_matches(test_column, '([0-9\.]*)'))[1]::float AS float_column
> FROM test_table
> ) foo
regexp_matches() returns a SETOF text[]
If it is in a FROM then each row of the set gets doubled and a single row
per input is output.
If it is in the SELECT-list that doesn't work. You have to use a scalar
subquery to make it work.
SELECT
(SELECT (regexp_matches('1.3', '([0-9\.]*)'))[1])::float
+
(SELECT (regexp_matches('2.3', '([0-9\.]*)'))[1])::float
;
Suggest wrapping it in a function - or making a "regexp_matches_single"
function that behaves similarly but returns a single text[] instead of a
SETOF text[]
David J.
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