/**
 * postgres-mcp - WHERE Clause Validation
 *
 * Validates WHERE clause parameters to prevent SQL injection.
 * Uses a blocklist approach to reject dangerous patterns while
 * allowing legitimate complex conditions.
 */
/**
 * Error thrown when an unsafe WHERE clause is detected
 */
export declare class UnsafeWhereClauseError extends Error {
    constructor(reason: string);
}
/**
 * Validates a WHERE clause for dangerous SQL patterns.
 *
 * This function uses a blocklist approach to detect and reject
 * common SQL injection patterns. It allows legitimate complex
 * conditions while blocking obvious attack vectors.
 *
 * Uses a two-phase approach for performance:
 * 1. Fast path: single combined regex test (covers 99%+ of safe queries)
 * 2. Slow path: individual pattern iteration for specific error messages
 *
 * @param where - The WHERE clause to validate
 * @throws UnsafeWhereClauseError if a dangerous pattern is detected
 *
 * @example
 * validateWhereClause("price > 10");                    // OK
 * validateWhereClause("status = 'active' AND id < 100"); // OK
 * validateWhereClause("1=1; DROP TABLE users;--");      // Throws
 * validateWhereClause("1=1 UNION SELECT * FROM pg_shadow"); // Throws
 */
export declare function validateWhereClause(where: string): void;
/**
 * Validates and returns a safe WHERE clause.
 *
 * @param where - The WHERE clause to sanitize
 * @returns The validated WHERE clause (unchanged if safe)
 * @throws UnsafeWhereClauseError if a dangerous pattern is detected
 */
export declare function sanitizeWhereClause(where: string): string;
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