Quote strings and dates in psql query results output - postgresql

Question

Under the section \pset [ option [ value ] ] of the psql docs, I can set various settings to make my query results convenient for me.
I can, for example, approach a CSV-like output with:
\pset fieldsep ','
\pset footer off
\pset format unaligned
\pset null 'NULL'
Resulting in output like:
> WITH foo_tbl(foo,bar,baz)
> AS
> (
> VALUES
> ('foo', NULL, 1),
> (NULL, 'bar', 1)
> )
> SELECT * FROM foo_tbl;
foo,bar,baz
foo,NULL,1
NULL,bar,1
This is great, but I'd like strings and dates to be quoted, like this:
foo,bar,baz
'foo',NULL,1
NULL,'bar',1
Is this not possible with psql?
p.s. I know this kind of thing can be done with SQL clients like DBeaver, but that isn't in the scope of this question.

Answer 1

To generate CSV output, you can use the copy command rather than trying to tweak the output of a regular SELECT statement.
copy (
WITH foo_tbl (foo,bar,baz,dt) AS
(
VALUES
('foo', NULL, 1, date '2020-01-02'),
(NULL, 'bar', 1, date '2020-03-04')
)
SELECT *
FROM foo_tbl
) to stdout
with (format csv, quote '''', header, null 'NULL', force_quote (foo, dt) );
Will generate the following output
foo,bar,baz,dt
'foo',NULL,1,'2020-01-02'
NULL,bar,1,'2020-03-04'
I am not aware of an option that will quote only dates and strings, but not numbers, so using force_quote and specifying the columns to quote is the only way to get them (always).
copy (...) to stdout is easier to use than it's psql sibling \copy because it allows multi-line queries.
To write everything into a file, you can use the \o command in psql
postgres=> \o data.csv
postgres=> copy (...) to stdout with (...);