The relational database model was a huge leap forward from the network database model.
關(guān)系數(shù)據(jù)庫模型是網(wǎng)絡(luò)數(shù)據(jù)庫模型的一個(gè)巨大飛躍。
Instead of relying on a parent-child or owner-member relationship, the relational model allows any file to be related to any other by means of a common field.
關(guān)系模型不依賴于父子關(guān)系或所有者-成員關(guān)系，而是允許任何文件通過公共字段與任何其他文件相關(guān)聯(lián)。
Suddenly, the complexity of the design was greatly reduced because changes could be made to the database schema without affecting the system's ability to access data.
突然，設(shè)計(jì)的復(fù)雜性大大降低，因?yàn)榭梢栽诓挥绊懴到y(tǒng)訪問數(shù)據(jù)能力的情況下對數(shù)據(jù)庫模式進(jìn)行更改。
And because access was not by means of paths to and from files, but from a direct relationship between files, new relations between these files could easily be added.
并且由于訪問不是通過文件之間的路徑，而是通過文件之間的直接關(guān)系，因此可以輕松地添加這些文件之間的新關(guān)系。
In 1970, when E.F. Codd developed the model, it was thought to be impractical.
1970年，當(dāng)e.f.Codd開發(fā)了這個(gè)模型，被認(rèn)為是不切實(shí)際的
The increased ease of use comes at a large performance penalty, and the hardware in those days was not able to implement the model.
增加的易用性帶來了很大的性能損失，并且當(dāng)時(shí)的硬件無法實(shí)現(xiàn)該模型。
Since then, of course, hardware has taken huge strides to where today, even the simplest computers can run sophisticated relational database management systems.
當(dāng)然，從那以后，硬件已經(jīng)取得了巨大的進(jìn)步，即使是最簡單的計(jì)算機(jī)也可以運(yùn)行復(fù)雜的關(guān)系數(shù)據(jù)庫管理系統(tǒng)。
Relational databases go hand-in-hand with the development of SQL.
關(guān)系數(shù)據(jù)庫與SQL的開發(fā)齊頭并進(jìn)。
The simplicity of SQL - where even a novice can learn to perform basic queries in a short period of time - is a large part of the reason for the popularity of the relational model.
SQL的簡單性 -- 即使是新手也可以在短時(shí)間內(nèi)學(xué)習(xí)執(zhí)行基本查詢 -- 是關(guān)系模型流行的很大一部分原因。

The two tables below relate to each other through the product_code field. Any two tables can relate to each other simply by creating a field they have in common.
下表通過product_code字段相互關(guān)聯(lián)。任何兩個(gè)表都可以通過創(chuàng)建它們共有的字段來相互關(guān)聯(lián)。
Table 1

Table 2