/**
 * SQL Expressions
 *
 * Type-safe SQL expressions for default values and other uses.
 * Provides a `t` helper with common expressions.
 */
/**
 * Represents a raw SQL expression (not a literal value).
 */
export declare class SqlExpression {
    readonly sql: string;
    constructor(sql: string);
    toString(): string;
    /**
     * Check if a value is a SQL expression.
     */
    static isExpression(value: unknown): value is SqlExpression;
}
/**
 * Helper object for common SQL expressions.
 * Use in migrations: `table.timestamp('createdAt').defaultValue(t.now())`
 */
export declare const t: {
    /**
     * Current timestamp (NOW() or CURRENT_TIMESTAMP depending on dialect).
     */
    now(): SqlExpression;
    /**
     * Current date (CURRENT_DATE).
     */
    currentDate(): SqlExpression;
    /**
     * Current time (CURRENT_TIME).
     */
    currentTime(): SqlExpression;
    /**
     * NULL value.
     */
    null(): SqlExpression;
    /**
     * Boolean true.
     */
    true(): SqlExpression;
    /**
     * Boolean false.
     */
    false(): SqlExpression;
    /**
     * Generate UUID (Postgres: gen_random_uuid(), MySQL: UUID()).
     */
    uuid(): SqlExpression;
    /**
     * Auto-generate UUID for MySQL.
     */
    mysqlUuid(): SqlExpression;
    /**
     * Raw SQL expression.
     * Use for custom expressions not covered by helpers.
     */
    raw(sql: string): SqlExpression;
    /**
     * String literal with proper escaping.
     */
    literal(value: string): SqlExpression;
    /**
     * Numeric literal.
     */
    number(value: number): SqlExpression;
    /**
     * Empty JSON object.
     */
    emptyObject(): SqlExpression;
    /**
     * Empty JSON array.
     */
    emptyArray(): SqlExpression;
    /**
     * MySQL: ON UPDATE CURRENT_TIMESTAMP.
     */
    onUpdateNow(): SqlExpression;
};
/**
 * Format a default value for SQL.
 * Handles SqlExpression vs literal values.
 */
export declare function formatDefaultValue(value: unknown): string;
//# sourceMappingURL=expressions.d.ts.map