Structured Query Language (SQL) Parser

Brief description

This project implements a simple SQL SELECT queries parser written in Rust using the pest crate. It supports a subset of SQL with common features such as SELECT, FROM, WHERE, JOIN, GROUP BY, and basic aggregate functions like SUM, AVG, COUNT, etc. The goal of this parser is to convert SQL-like queries into a structured representation that can later be used for query optimization, execution, or further processing.

Example queries

1. SELECT name, age FROM users WHERE age > 21;
2. SELECT name, COUNT(*) FROM users GROUP BY name;
3. SELECT u.name, o.amount FROM users u JOIN orders o ON u.id = o.user_id;

Technical description of the parsing process

The parser uses the pest crate to process SQL SELECT queries. It follows these steps:

1. Tokenization: The input query is split into tokens based on SQL syntax rules (keywords, identifiers, operators, etc.).
2. Parsing: These tokens are matched against grammar rules to structure the query correctly.
3. Query Representation: The parsed query is transformed into a structured format (an AST - Abstract Syntax Tree) for further processing, like execution or optimization.