Thread: Fwd: replace text occurrences loaded from table

Von: Igor Romanchenko <igor.a.romanchenko@gmail.com>

Betreff: Aw: [SQL] replace text occurrences loaded from table

Datum: 30. Oktober 2012 14:38:57 MEZ

An: jan zimmek <jan.zimmek@web.de>

Hello,

you can try somethig like

UPDATE tmp_messages

SET message = regexp_replace(

   message,

   (SELECT string_agg(var,'|') FROM tmp_vars),

   'XXX',

   'g')

The idea is to form a single replacement string and to do all the replacements in one go.

1 scan to form the replacement string (something like 'ABC|XYZ|VAR123').

1 scan and update do all the changes.

On Tue, Oct 30, 2012 at 1:45 PM, jan zimmek <jan.zimmek@web.de> wrote:

hello,

i am actually trying to replace all occurences in a text column with some value, but the occurrences to replace are defined in a table. this is a simplified version of my schema:

create temporary table tmp_vars as select var from (values('ABC'),('XYZ'),('VAR123')) entries (var);
create temporary table tmp_messages as select message from (values('my ABC is XYZ'),('the XYZ is very VAR123')) messages (message);

select * from tmp_messages;

my ABC is XYZ -- row 1
the XYZ is very VAR123 -- row 2

now i need to somehow update the rows in tmp_messages, so that after the update i get the following:

select * from tmp_messages;

my XXX is XXX -- row 1
the XXX is very XXX -- row 2

i have implemented a solution in plpgsql by doing a nested for-loop over tmp_vars and tmp_messages, but i would like to know if there is a more efficient way to solve this problem ?


best regards
jan

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