Обсуждение: varchar::bytea fails when varchar contains backslash

Hello,

I wanted to look into a column of type varchar converting the content
with ::bytea to a hex string, but this fails when the column contains a
backslash:

psql -Usisis -dtestdb
psql (14.1)
Geben Sie »help« für Hilfe ein.

testdb=# select trenn from sik_fstab where name='EdvSelKenn';
             trenn
-------------------------------
 ; :,.-!@%&/()=?'*+#<>[\]{|}&"
 ; :,.-!@%&/()=?'*+#<>[\]{|}&"
(2 Zeilen)

testdb=# select trenn::bytea from sik_fstab where name='EdvSelKenn';
ERROR:  invalid input syntax for type bytea

Why is this?

    matthias
-- 
Matthias Apitz, ✉ guru@unixarea.de, http://www.unixarea.de/ +49-176-38902045
Public GnuPG key: http://www.unixarea.de/key.pub

    Matthias Apitz wrote:

> I wanted to look into a column of type varchar converting the content
> with ::bytea to a hex string, but this fails when the column contains a
> backslash:

Yes, casting from text to bytea cannot be used for that.
The convert_to() function must be used instead.

From the doc at
https://www.postgresql.org/docs/current/functions-binarystring.html

convert_to ( string text, dest_encoding name ) → bytea

Converts a text string (in the database encoding) to a binary string encoded
in encoding dest_encoding (see Section 24.3.4 for available conversions).

convert_to('some_text', 'UTF8') → \x736f6d655f74657874



Best regards,
--
Daniel Vérité
PostgreSQL-powered mailer: https://www.manitou-mail.org
Twitter: @DanielVerite