P0002ERRORTier 2 — Caution✅ HIGH confidence

no_data_found

Category: PL/pgSQL ErrorVersions: All PostgreSQL versions with PL/pgSQL

What this means

A SELECT INTO or FETCH statement inside a PL/pgSQL function returned no rows, and the function was not written to handle that case gracefully.

Why it happens

1SELECT INTO in PL/pgSQL returned zero rows and STRICT mode is used, or explicit check raises exception
2FETCH on a cursor that has been exhausted
3Function expected exactly one row from a query but the table is empty or the WHERE clause matched nothing

How to reproduce

PL/pgSQL function using SELECT INTO STRICT or explicit NOT FOUND check

trigger — this will ERROR

CREATE OR REPLACE FUNCTION get_user(uid int) RETURNS text AS $
DECLARE
  uname text;
BEGIN
  SELECT name INTO STRICT uname FROM users WHERE id = uid;
  RETURN uname;
END;
$ LANGUAGE plpgsql;

SELECT get_user(99999);  -- user 99999 does not exist

ERROR: P0002: query returned no rows

Fix 1: Handle NOT FOUND in an EXCEPTION block

Zero rows is a valid expected outcome

fix

BEGIN
  SELECT name INTO STRICT uname FROM users WHERE id = uid;
EXCEPTION WHEN no_data_found THEN
  RETURN NULL;  -- or a default value
END;

Why this works

Catches P0002 and returns a sensible default instead of propagating the error

Fix 2: Use SELECT INTO without STRICT and check FOUND

Zero rows is acceptable and you want to handle it inline

fix

SELECT name INTO uname FROM users WHERE id = uid;
IF NOT FOUND THEN
  RETURN NULL;
END IF;

Why this works

Without STRICT, SELECT INTO does not raise P0002; use the FOUND variable instead

What not to do

✗

Do not use SELECT INTO STRICT for queries that may legitimately return no rows without handling no_data_found

Why it's wrong: Will raise an unhandled exception on empty results

Sources

📚 Official docs: https://www.postgresql.org/docs/current/plpgsql-statements.html#PLPGSQL-STATEMENTS-SQL-ONEROW

🔧 Source ref: https://www.postgresql.org/docs/current/errcodes-appendix.html

📖 Further reading:

Confidence assessment

✅ HIGH confidence

Well-documented PL/pgSQL error; extremely common in production stored procedures.