Plain text, flat file, 及flat-file database 如何翻译

经常遇到Plain text, flat file, 及flat-file database 这三个词，但不知翻译成什么样的中文好。请大家多指教。
英文意思我已经找到了：
(1) plain text
Refers to textual data in ASCII format. Plain text is the most portable format because it is supported by nearly every application on every machine. It is quite limited, however, because it cannot contain any formatting commands.
In cryptography, plain text refers to any message that is not encrypted. Contrast with cipher text.

Plain text is also called clear text
(2)flat file

A file that has no structured interrelationship between its data records. A text document without formatting structure is considered a flat file. For example, a word processing document that has been saved as "text only" is saved without markup tags or formatting elements such as bold, italic or other font specifications and information that specifies what style to make a certain line that is used as a heading. The flat file only contains the lines of text without regard to the visual presentation of the data on the page.

(3) flat-file database
A relatively simple database system in which each database is contained in a single table. In contrast, relational database systems can use multiple tables to store information, and each table can have a different record format.

我的翻译是：
(1) plain text 纯文本
(2) flat- file 无格式文件(觉着这个最难)
(3) flat-file database 非关系数据库