Message-ID: <4c3c231f54e9d6bae4cba0c84079f000901da653.camel@cybertec.at>
Subject: Re: How to surround a selected value with double quotes?
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: "Subramanian,Ramachandran" <ramachandran.subramanian@alte-leipziger.de>,
  "pgsql-novice@lists.postgresql.org"	 <pgsql-novice@lists.postgresql.org>
Date: Mon, 22 Jun 2026 10:26:24 +0200
In-Reply-To: <b91203df511b42c6850ec55c84ab6525@alte-leipziger.de>
References: <b91203df511b42c6850ec55c84ab6525@alte-leipziger.de>
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On Mon, 2026-06-22 at 07:46 +0000, Subramanian,Ramachandran wrote:
> I wrote a script to analyze and run vacuum on tables that need it.

I assume you are talking about a bash script.

> Sadly at the time I wrote the script, I never expected a schema name to b=
e pure numbers.=C2=A0
> =C2=A0
> So my Script does not work now.
> =C2=A0
> I want to add double quote marks to each schema name and table name selec=
t.
> I tried using the CONCAT function, but it does not work as I expected it =
to.
> =C2=A0
> I would be grateful if someone can help me understand the mistake I am ma=
king with the CONCAT.

You are a victim of (self-inflicted) SQL injection.

Just surrounding the schema name with double quotes is not enough.
What if the schema name itself contains a double quote?

You should use PostgreSQL's functions to properly quote an identifier.
With a shell script, I think your only choice is to use SQL:

#!/bin/bash

schema=3D'12345  43'
table=3D'tab"567'

quoted_schema=3D$(psql -Atq -v var=3D"$schema" <<EOF
SELECT quote_ident(:'var');
EOF
)

quoted_table=3D$(psql -Atq -v var=3D"$table" <<EOF
SELECT quote_ident(:'var');
EOF
)

sql=3D"SELECT col FROM $quoted_schema.$quoted_table"


Yours,
Laurenz Albe