🗄️ SQL Compiler: Flex / Bison + Tkinter GUI

Write SQL. Compile it. See errors in real time.

A fully functional SQL compiler built from scratch using Flex (lexer) and Bison/Yacc (parser), with a dark-themed Python Tkinter GUI. Runs on Linux type or load SQL queries and get instant syntax validation with detailed error messages including line number and token location.

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✨ Features

• 📝 Lexer (Flex) : tokenizes SQL keywords, identifiers, operators, and symbols
• 🧩 Parser (Bison/Yacc) : validates SQL grammar rules
• ✅ Supported SQL statements:
  • SELECT.. with * or column list, single or multiple tables
  • INSERT INTO ... VALUES
  • UPDATE ... SET ... WHERE
  • DELETE FROM ... WHERE
  • CREATE TABLE / DATABASE
  • DROP TABLE / DATABASE
  • ALTER TABLE ... ADD
• 🔴 Detailed error messages : line number + unexpected token + expected token
• 🖥️ Tkinter GUI : dark VS Code-inspired interface with INPUT and OUTPUT panels
• 📂 File loading : load .sql or .txt files directly into the editor
• 🔁 Case-insensitive : SQL keywords work in any case (SELECT, select, Select)

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📸 Screenshots

Empty Interface	Error Detection	Build Commands

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🏗️ Project Structure

sql-compiler/
├── lexer.l          # Flex lexer : tokenization rules
├── parser.y         # Bison parser : grammar rules + error reporting
├── interface.py     # Python Tkinter GUI
└── screenshots/

⚙️ Generated files (lex.yy.c, parser.tab.c, parser.tab.h, sql_compiler) are excluded from the repo build them locally using the commands below.

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🚀 Getting Started

Prerequisites (Linux/Ubuntu)

sudo apt install flex bison gcc python3

Build & Run

# Step 1 : Generate lexer
flex lexer.l

# Step 2 : Generate parser
bison -d parser.y

# Step 3 : Compile
gcc parser.tab.c lex.yy.c -o sql_compiler

# Step 4 : Launch GUI
python3 interface.py

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🔬 How It Works

1. User types SQL in the INPUT panel or loads a .sql file
2. GUI calls the compiled sql_compiler binary via subprocess
3. Flex tokenizes the input identifies keywords, identifiers, operators
4. Bison validates the token stream against SQL grammar rules
5. Valid statements print: Line X: Valid SELECT (or INSERT, CREATE, etc.)
6. Invalid statements print: Line X | Error: syntax error | (At token: 'TOKEN')
7. Output displayed in color green for success, red for errors

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💡 Example

Input:

CREATE DATABASE my_data;
SELECT * FROM users;
DROP TABLE old_records;
INSERT INTO logs VALUES (500);
SELECT name FROM users
DROP DATABASE temp;

Output:

ERRORS
Line 6 | Error: syntax error, unexpected DROP, expecting SEMICOLON | (At token: 'DROP')

Line 5 is missing a semicolon — the compiler catches it precisely.

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🛠️ Tech Stack

Layer	Technology
Lexer	Flex (Fast Lexical Analyzer)
Parser	Bison / Yacc
Compiler	GCC
GUI	Python Tkinter
Platform	Linux / Lubuntu VM

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👤 Author

Sakni Tasnim
Telecommunications & Computer Engineering Student
🔗 GitHub • LinkedIn

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📄 License

Feel free to use, modify, and build on this project.