SQL Parsing And Translation Oriented To Database Security

The increase of data breach attracted more and more attention to database security. Because relational database is very complex and it lies in the center of an information system, its security is very difficult to guaranty. SQL’s accurate parsing is an important basis of database security, because it could quickly analyse user’s targets, methods and other session information. Based on SQL parsing, we can establish access control rules to reduce or avoid data breach from database. It is possible to translate SQL to natural language based on SQL parsing, which can help common users to analyze database activities and identify risks.The main task of SQL parsing is the construction of SQL Lexer and SQL Parser. Reported SQL parsing are built based on Yacc and Lex. Yacc and Lex use LR analysis method, which leads their performance is relatively better but relatively more difficulty to build. On the contrary, by exploring LL grammer, we can quickly and easily generate SQL lexer and parser.Firstly, this paper summarizes the general process of the construction of SQL Lexer and SQL Parser, and compares LR analysis method and LL analysis method. SQL EBNF description of lexical and syntactic analysis can be used for constructing the rules of LL analysis method. Taking advantage of ANTLR tool generates the SQL Lexer and Parser. Then, we use SQL Lexer and SQL Parser convert SQL statement into an abstract syntax tree. By parsing abstract syntax tree, translation module translates the SQL statements into natural language. Finally, SQL parsing and the function of translation are applied to the Database Audit and Firewall System.