How to use string with apostrophe in function variable plpgsql - sql

Question

Hello I am having trouble querying when I have apostrophe in my where clause in postgresql using pgpsql function, I know that manually I could do something like:
select 'author''s'
however my word is stored in a variable, here is my function:
CREATE OR REPLACE FUNCTION public.fn_inserir_doc(caminho_arqv text, conteudo text)
RETURNS void
LANGUAGE plpgsql
AS $function$
declare
conteudo_array text array;
palavra text;
begin
execute 'insert into documento(caminho)
select ''' || caminho_arqv || '''
where not exists(select id
from documento
where caminho='''||caminho_arqv||''')';
conteudo_array := regexp_split_to_array(conteudo, E'\\s+');
FOREACH palavra in array conteudo_array
loop
if length(palavra) >=3 then
raise notice 'palavra: %', palavra;
execute 'insert into termo(descricao)
select ''' || palavra || '''
where not exists(
select id from termo
where descricao='''||palavra||''')';
execute 'insert into documento_termo(id_termo, id_documento, frequencia)
select t.id, d.id, 1
from termo t
cross join documento d
where t.descricao = '''|| palavra ||'''
and d.caminho = '''|| caminho_arqv ||'''
on conflict (id_termo, id_documento) do update set frequencia = documento_termo.frequencia + 1;';
end if;
end loop;
end;
$function$
The following sample is the one that has the problem:
select id from termo
where descricao='''||palavra||'''
because palavra contains single quote

Answer 1

Use dollar quoting and the function format(). Example:
create or replace function test(str text)
returns setof text language plpgsql as $$
begin
-- instead of this:
-- return query execute 'select '''||str||'''::text';
-- use:
return query execute format(
$fmt$
select %L::text
$fmt$, str);
end $$;
select * from test('O''Brian');
test
---------
O'Brian
(1 row)