/**
 * Quote a single identifier (table, column, alias) with backticks.
 * Already-quoted identifiers (e.g. "`users`") are returned unchanged.
 */
export declare function quoteIdentifier(identifier: string): string;
/**
 * Quote a possibly qualified identifier: "table.field" -> `table`.`field`.
 * A bare "*" (or "table.*") is kept as a wildcard.
 */
export declare function quoteQualified(identifier: string): string;
/**
 * Build a column reference, prefixing the table when one is given and the
 * field is not already qualified.
 */
export declare function columnRef(field: string, table?: string): string;
/**
 * Escape a value for use inside a single-quoted SQL string literal.
 */
export declare function escapeStringLiteral(value: string): string;
export declare function sqlLogicalOperator(operator?: string): "AND" | "OR";
export declare function sqlOrderStrategy(strategy?: string): "ASC" | "DESC";
export declare function sqlRawComparison(comparison: string): string;
export declare function sqlJoinType(joinType: string): string;
/**
 * Validate a LIMIT / OFFSET / page value as a non-negative integer.
 */
export declare function sqlNonNegativeInt(value: unknown, name: string): number;