/**
 * SQL Mode 2 — SQL-Specific Guardrails
 *
 * Checks SQL AST for dangerous patterns before execution.
 */
interface AstNode {
    type?: string;
    keyword?: string;
    where?: unknown;
    limit?: unknown;
    from?: Array<{
        table?: string;
    }>;
    table?: Array<{
        table?: string;
    }> | string;
    columns?: unknown;
    set?: unknown;
}
/**
 * Check SQL AST for guardrail violations.
 * Throws StrictDBError if blocked.
 */
export declare function checkSqlGuardrails(ast: AstNode, sql: string, config?: {
    limitRequired: boolean;
    emptyFilter: boolean;
}): void;
/**
 * Check for = NULL / != NULL comparisons in WHERE clause.
 * These should use IS NULL / IS NOT NULL instead.
 */
export declare function checkNullComparisons(where: unknown, sql: string): void;
export {};
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