42P22ERRORTier 2 — Caution✅ HIGH confidence

indeterminate datatype

Category: Syntax Error or Access Rule ViolationVersions: All Postgres versions

What this means

SQLSTATE 42P22 is a Postgres-specific error raised when Postgres cannot determine the data type of an expression — typically an untyped literal or parameter — from the context.

Why it happens

1A bare untyped literal (e.g., NULL without a cast) in a context where Postgres cannot infer the type
2An untyped parameter ($1) in a prepared statement where the type cannot be inferred from context

How to reproduce

SELECT with an untyped NULL in a function argument.

trigger — this will ERROR

SELECT * FROM some_function(NULL); -- which NULL type?

ERROR: could not determine data type of parameter $1

Fix 1: Cast the untyped literal or parameter to the expected type

When an untyped literal causes type inference to fail.

fix

SELECT * FROM some_function(NULL::TEXT);
-- or for prepared statement parameters:
-- PREPARE stmt (TEXT) AS SELECT * FROM some_function($1);

Why this works

Explicit type casting removes the ambiguity by telling Postgres exactly what type the expression is.

Sources

📚 Official docs: https://www.postgresql.org/docs/current/errcodes-appendix.html

🔧 Source ref: Class 42 — Syntax Error or Access Rule Violation (Postgres-specific)

Confidence assessment

✅ HIGH confidence

Postgres-specific. Stable across versions.