pola-rs/polars · error · SQLSyntax

negative ordinal values are invalid for

Error message

negative ordinal values are invalid for {}; found -{}

What it means

In polars-sql, ORDER BY (and similar) clauses accept ordinal literals like ORDER BY 2. A negative number was given as the ordinal reference. The library rejects it with a SQLSyntax error since -1 is not a valid column ordinal.

Solutions

1. Remove the minus sign or use a positive integer between 1 and the number of selected columns.
2. If descending order was intended, use ORDER BY 2 DESC instead of a negative ordinal.
3. Validate/abs() any programmatically supplied ordinal before interpolating it into the SQL string.

Example fix

// before
ctx.execute("SELECT a, b FROM t ORDER BY -2")
// after
ctx.execute("SELECT a, b FROM t ORDER BY 2 DESC")

ord = -2
assert isinstance(ord, int) and 1 <= ord <= n_selected_columns, f"ordinal must be in 1..{n_selected_columns}"
sql = f"SELECT a, b FROM t ORDER BY {ord} DESC"

def valid_ordinal(v: int, n_cols: int) -> bool:
    return isinstance(v, int) and 1 <= v <= n_cols

try:
    ctx.execute(sql)
except sqlglot_errors / pl.exceptions.InvalidOperationError as e:
    raise ValueError(f"bad ORDER BY ordinal in: {sql}") from e

When it happens

Trigger: Executing SQL via SQLContext.execute/execute_registered with e.g. 'SELECT a FROM t ORDER BY -2' — the expr_or_ordinal helper in process_order_by parses a negative numeric literal as the ordinal.

Common situations: Writing SQL by hand with a minus typo, or programmatically generating ORDER BY from a signed index variable that happens to be negative.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• only a single SQL query string is accepted for adbc, got a
• 'pre_execution_query' is only supported in connectorx…
• statements are not valid 'read' queries
• {response["result"]}
• unrecognised frame type

AI-assisted analysis of pola-rs/polars@fe841f959e (2026-09-18). Data as JSON: /api/errors/00959b67234b880c. Report an issue: GitHub.

Appendix: source

Thrown at crates/polars-sql/src/context.rs:567

        clause: &str,
    ) -> PolarsResult<Expr> {
        match e {
            SQLExpr::UnaryOp {
                op: SQLUnaryOperator::Minus,
                expr,
            } if matches!(
                **expr,
                SQLExpr::Value(ValueWithSpan {
                    value: SQLValue::Number(_, _),
                    ..
                })
            ) =>
            {
                if let SQLExpr::Value(ValueWithSpan {
                    value: SQLValue::Number(ref idx, _),
                    ..
                }) = **expr
                {
                    Err(polars_err!(
                    SQLSyntax:
                    "negative ordinal values are invalid for {}; found -{}",
                    clause,
                    idx
                    ))
                } else {
                    unreachable!()
                }
            },
            SQLExpr::Value(ValueWithSpan {
                value: SQLValue::Number(idx, _),
                ..
            }) => {
                // note: sql queries are 1-indexed
                let idx = idx.parse::<usize>().map_err(|_| {
                    polars_err!(
                        SQLSyntax:

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