Following the convention of the SQL standard, identifiers in DuckDB are case-insensitive. However, each character’s case (uppercase/lowercase) is maintained as entered by the user.

Examples

The case entered by the user is preserved even if a query uses different cases when referring to the identifier:

CREATE TABLE CosPi AS SELECT cos(pi()) AS CosineOfPi;
SELECT cosineofpi FROM CosPi;

┌────────────┐
│ CosineOfPi │
│   double   │
├────────────┤
│       -1.0 │
└────────────┘

In case of a conflict, when the same identifier is spelt with different cases, one will be selected randomly. For example:

CREATE TABLE t1(idfield int, x int);
CREATE TABLE t2(IdField int, y int);
SELECT * FROM t1 NATURAL JOIN t2;

┌─────────┬───────┬───────┐
│ idfield │   x   │   y   │
│  int32  │ int32 │ int32 │
├─────────────────────────┤
│         0 rows          │
└─────────────────────────┘