SQLSTATE 42601 ERROR

syntax_error subquery must return only one column — 42601

PostgreSQL error 42601 — subquery must return only one column. A statement was rejected because of how it was written or what value it carried — not because of mis

PG 14 · 15 · 16 · 17 · 18 Reviewed Jun 2026

Incident Brief

What happened: A statement was rejected because of how it was written or what value it carried — not because of missing objects or permissions:

ERROR: subquery must return only one column

Immediate action: 1. Read the message — it states precisely what PostgreSQL objected to.
2. Select a single column in the subquery, or restructure as a row/tuple/">record or a join if you genuinely need multiple columns.
3.

The fix

Copy-paste · works on PG 14–18
  1. Read the message — it states precisely what PostgreSQL objected to.
  2. Select a single column in the subquery, or restructure as a row/record or a join if you genuinely need multiple columns.
  3. Re
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