Re: Passing function parameters to regexp_replace

On Saturday 17. September 2011 19.07.03 Tim Landscheidt wrote:
> Leif Biberg Kristensen <leif(at)solumslekt(dot)org> wrote:
>
> > UPDATE sources SET source_text = regexp_replace(source_text,
> > E'n="(.*?)$1(.*?)"', E'n="\\1$2\\2"', 'g') where source_text like
> > '%n="%$1%">%'
>
> Try:
> > UPDATE sources SET source_text = regexp_replace(source_text,
> > CONCAT(E'n="(.*?)', $1, E'(.*?)"'), CONCAT(E'n="\\1', $2, '\\2"', 'g')
> > where source_text like CONCAT('%n="%', $1, '%">%')

The function CONCAT doesn't exist i PostgreSQL. And I can't get it to work
with EXECUTE and standard concatenation either:

pgslekt=> CREATE OR REPLACE FUNCTION update_nametags(TEXT, TEXT) RETURNS VOID
AS $$
pgslekt$> BEGIN
pgslekt$> EXECUTE $_$
pgslekt$> UPDATE sources SET source_text =
pgslekt$> REGEXP_REPLACE(
pgslekt$> source_text,
pgslekt$> E'n="(.*?)' || $1 || '(.*?)"',
pgslekt$> E'n="\\1' || $2 || '\\2"', 'g'
pgslekt$> )
pgslekt$> WHERE source_text LIKE E'%n="%' || $1 || '%">%'
pgslekt$> $_$;
pgslekt$> END
pgslekt$> $$ LANGUAGE PLPGSQL VOLATILE;
CREATE FUNCTION
Time: 1,105 ms
pgslekt=> select update_nametags('Brynild','Brynil');
WARNING: nonstandard use of \\ in a string literal
LINE 6: E'n="\\1' || $2 || '\\2"', 'g'
^
HINT: Use the escape string syntax for backslashes, e.g., E'\\'.
QUERY:
UPDATE sources SET source_text =
REGEXP_REPLACE(
source_text,
E'n="(.*?)' || $1 || '(.*?)"',
E'n="\\1' || $2 || '\\2"', 'g'
)
WHERE source_text LIKE E'%n="%' || $1 || '%">%'

CONTEXT: PL/pgSQL function "update_nametags" line 2 at EXECUTE statement
ERROR: there is no parameter $1
LINE 5: E'n="(.*?)' || $1 || '(.*?)"',
^
QUERY:
UPDATE sources SET source_text =
REGEXP_REPLACE(
source_text,
E'n="(.*?)' || $1 || '(.*?)"',
E'n="\\1' || $2 || '\\2"', 'g'
)
WHERE source_text LIKE E'%n="%' || $1 || '%">%'

CONTEXT: PL/pgSQL function "update_nametags" line 2 at EXECUTE statement

> If $1 and $2 (can) include meta characters, you have to es-
> cape them properly.
>
> Please consider that regexp_replace() uses POSIX Regular
> Expressions while LIKE uses a different syntax. If possible,
> I would replace the LIKE expression with its "~" equivalent
> so chances of confusion are minimized.

The intended use is to replace a short string like 'Jacob' with 'Jakob' within
a specific XML attribute value.

regards, Leif