SQL is a declarative language in the sense that only the data of interest is described in the program, not the algorithm for obtaining the data.
SQL在某种意义上来说是一种在程序中只描述感兴趣的数据的声明性语言，而不是为获得数据的算法。
2
If you wanted to create a program that tracks the activity of a chess club, you might use a data structure that would be described by the following Perl code.
如果您想创建一个追踪国际象棋俱乐部活动的程序，则可以使用由以下Perl代码描述的数据结构。
3
The main data structure used in the program is given, By means of program flow chart, the program is described in detail.