import { ConditionParam, Constructable, SelectParam } from "./util.ts";
import { SqlSelectable } from "./SqlStatement.ts";
/**
 * 获取对象数组中的 key 的集合
 * @param keepUndefinedKey - 是否保留值为 undefined 的 key
 */
export declare function getObjectListKeys(objectList: readonly any[], keepUndefinedKey?: boolean): Set<string>;
/**
 * 生成条件语句
 */
export declare function condition(conditions?: Constructable<ConditionParam | void>, type?: "AND" | "OR"): string;
/**
 * 生成 WHERE 语句
 * @public
 * @example
 * ```ts
 * where(['a=1','b=2']) // "\nWHERE a=1 AND b=2"
 * where(['a=1','b=2'],"OR") // "\nWHERE a=1 OR b=2"
 * where("a=1 OR b=2") // "\nWHERE a=1 OR b=2"
 * where(()=>"a=1 OR b=2") // "\nWHERE a=1 AND b=2"
 * where([]) // ""
 * where(undefined) // ""
 * ```
 */
export declare function whereToString(conditions?: Constructable<ConditionParam | void>, type?: "AND" | "OR"): string;
export declare function createUpdateSetFromObject(set: Record<string, string | undefined>, prefix?: string): string;
export declare function selectableToString(selectable: Constructable<SqlSelectable | string>, as?: string): string;
export declare function returningToString(returns: Constructable<SelectParam | "*">): string;