HSQLDB v.2.3.0: USING predicate working as intended? - sql

Question

The following query when executed against snapshot 50 of HSQLDB 2.3.0 produces an error. The error message is "Error: duplicate column name in derived table: INST_ID"
SELECT c.lastname, to_date_string(c.dob), i.itag|| ': ' ||
m.mrn, to_date_string(en.dofs),
to_date_string(en.dols), pa.payertag,
y.dxname, d.icd9, d.icd10, d.icd10name,
to_datetime_string(s.dos), r.cpt, r.rxname, p.lastname || ', ' ||
p.firstname
FROM Encounters AS en
INNER JOIN Clients AS c USING ( cli_id )
INNER JOIN Client_MRNs AS m ON c.defmrn_id = m.mrn_id
INNER JOIN Institutions AS i USING ( inst_id )
INNER JOIN Payers AS pa USING ( payer_id )
INNER JOIN Encounter_DXs AS x USING ( enc_id )
INNER JOIN Diagnoses AS d USING ( dx_id )
INNER JOIN DXSynonyms AS y ON d.defsyn_id = y.syn_id
INNER JOIN Services AS s USING ( enc_id )
INNER JOIN RXCodes AS r USING ( rx_id )
INNER JOIN Providers AS p USING ( prov_id )
WHERE (s.dos >= 56453 AND s.dos < 56461)
ORDER BY c.lastname, en.dofs, s.dos;
However, when I execute the same query but replace all the USING predicates with ON ... = phrases it executes successfully:
SELECT c.lastname, to_date_string(c.dob), i.itag|| ': ' ||
m.mrn, to_date_string(en.dofs),
to_date_string(en.dols), pa.payertag,
y.dxname, d.icd9, d.icd10, d.icd10name,
to_datetime_string(s.dos), r.cpt, r.rxname, p.lastname || ', ' ||
p.firstname
FROM Encounters AS en
INNER JOIN Clients AS c ON c.cli_id = en.cli_id
INNER JOIN Client_MRNs AS m ON c.defmrn_id = m.mrn_id
INNER JOIN Institutions AS i ON i.inst_id = m.inst_id
INNER JOIN Payers AS pa ON pa.payer_id = en.payer_id
INNER JOIN Encounter_DXs AS x ON x.enc_id = en.enc_id
INNER JOIN Diagnoses AS d ON d.dx_id = x.dx_id
INNER JOIN DXSynonyms AS y ON d.defsyn_id = y.syn_id
INNER JOIN Services AS s ON s.enc_id = en.enc_id
INNER JOIN RXCodes AS r ON r.rx_id = s.rx_id
INNER JOIN Providers AS p ON p.prov_id = s.prov_id
WHERE (s.dos >= 56453 AND s.dos < 56461)
ORDER BY c.lastname, en.dofs, s.dos;
Is this working as intended? I like using USING because it results in less verbose, cleaner code. I won't include the DDL for the tables right now (but can), because the queries are big and involve many tables, but there are three tables that have INST_ID fields. One table has it as the primary key, and the other two have foreign keys to it. Really the only difference in the queries is "ON" vs "USING".

Answer 1

After the first join, there is one INST_ID from ENCOUNTERS. After the second join, there is an additional one from CLIENTS_MRNS. The third join fails because of this duplication.