The Analysis And Realization Of Database Language SQL

The commercial database management software is developing quickly all these years recently, including Oracle, DB2, SQL Server; the middle and small database management software is also very popular, Postgresql and MySql being the most favorable one. However, in China there still remains the situation that we do not have our own database management software. As a student of Computer Science, to learn and master the technique in the realization of a database management system is significant both in research and appliance values.This article is based on the principle of compiler. After considered the process and theories of the complier, the article realized a basic structure used in DBMS and a SQL syntax analyzer as well. There are important aspects in this article as follow: the implementation of data store structure and the interface it provides to the upper database system. The data structure is realized by using an index file and a data file, while the interface is coded with C language; Use the theory of lexical analysis module and semantic analysis module and then use the tools Lex and Yacc to realize the SQL syntax analyzer, which is more efficiency and can be more correct during coding. In order to demonstrate the use of Lex and Yacc, the article also show the process of generating a traditional procedure language. And that give a good practical reference for the SQL syntax analyzer.