MVP - Interpreter

[FletcherDares]

SQL Interpreter MVP - Development Phases

Phase 1 - Basic table creation and data retrieval

• CREATE TABLE with basic columns and datatypes: Interpreter - AST Create Table Statement #3
• Basic INSERT (single row and multi row): Implement - AST Insert Into Statement #9
• Basic SELECT (no modifiers): Implement - AST Select Statement #11
• Refactor interpreter.current_token() to use Result instead of Option and use a peek method for consistency. Rename interpreter to parser: Refactor and add tests to parser module. #15
• Improve error messages from Parser: Fix error messages to display the value instead of token type #23

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Phase 2 - Core CRUD Operations

• Implement Logical AND & OR using RPN: Implement - AST Logical Operators #34
• Implement IN conditon and identifier = identifier: AST - Implement IN & Identifier = Identifier #35
• UPDATE statements: AST - Update Table Statement Generation #31
• DELETE statements: AST - Implement Delete Statement #32
• Refactor and add tests to individual helper methods in common.rs: AST - Refactor Parser Testing and Helpers #33

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Phase 3 - Improvements

• SQL Comments: Parser - SQL Comments \* ... *\ and -- ... #62
• WHERE clause generation refactor: AST - Refactor WHERE #60
• Table Improvements
  • DROP TABLE functionality
    • AST / DB - CREATE implement IF NOT EXISTS #55
  • ALTER TABLE functionality
    • DB / AST - ALTER TABLE implementation  #58
  • Database Transactions (Supported with actual diff tracking) Finished in AST - Transaction statements #66
  • Assert that duplicate columns cannot exists
• SELECT Improvements
  • Column & table aliases: AST - SELECT column and table aliasing #85
    • These need to be generalized to functions see the todo in AST - Improve Alias' #90
  • UNION, INTERSECT, EXCEPT statements: AST - Implement Set operators #47
  • DISTINCT
    • DB / AST - DISTINCT with SELECT statement #59
  • Aggregate functions (COUNT, SUM, AVG, MIN, MAX)
  • GROUP BY
  • JOINs

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Phase 4 - Constraints & Validation

• Add defaults to Inserts
• Column constraints (NOT NULL, PRIMARY KEY, UNIQUE, etc.)
• Table constraints (FOREIGN KEY, CHECK, etc.)
• Enhanced error handling and validation
• Syntax error detection and reporting
• Semantic validation (table exists, column exists, type mismatches)

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Other:

• Add unit testing to the interpreter.
• Refactor and add tests to parser module. #15