SDB: A Simple Relational Database Management System

The source files for the SQL DBMS, called SDB (which stands for a Simple Database System), are the following:

1. main.cc: The main program.
2. sql.y: The yacc grammar for the sql syntax.
3. sql.lex: The lex scanner to parse tokens.
4. ~fegaras/cse6331/optgen/basic.h: The Expr class, the list templates, etc; READ IT.
5. typecheck.h/.gen: This is the typechecking program.
6. optimizer.h/.gen: This is the actual optimizer. READ optimizer.gen.
7. evaluation.h/.gen: This is the in-memory evaluator; READ evaluation.h.
8. common.cc: it is included in optimizer; it contains code for memoization and tracing; don't mess with it.
9. company.sql: The company schema and data as they are described in Elmasri's book.
10. queries.sql: A sample of few queries against the company database.
11. database: The actual database state.

At this point, SDB compiles, optimizes, and executes (in memory) all SQL queries with simple predicates, unions, grouping, and aggregations.