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QUICKSTART.md

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LangDB Quick Start Guide

This guide will help you get started with LangDB in just a few minutes.

Prerequisites

  • Rust and Cargo installed (1.70+ recommended)
  • Basic knowledge of SQL

Installation

  1. Clone the repository:
git clone https://github.com/Okemwag/langdb.git
cd langdb
  1. Build the project:
cargo build --release
  1. Run LangDB:
cargo run --release

Your First Database

Once LangDB starts, you'll see the interactive prompt:

langdb>

Step 1: Create a Table

CREATE TABLE users (id INTEGER, name TEXT, email TEXT);

Step 2: Insert Data

INSERT INTO users VALUES (1, 'Alice', 'alice@example.com');
INSERT INTO users VALUES (2, 'Bob', 'bob@example.com'), (3, 'Charlie', 'charlie@example.com');

Step 3: Query Data

SELECT * FROM users;

Output:

| id | name      | email               |
+----+-----------+---------------------+
| 1  | 'Alice'   | 'alice@example.com' |
| 2  | 'Bob'     | 'bob@example.com'   |
| 3  | 'Charlie' | 'charlie@example.com' |

3 row(s) returned

Step 4: Filter Data

SELECT name, email FROM users WHERE id > 1;

Output:

| name      | email               |
+-----------+---------------------+
| 'Bob'     | 'bob@example.com'   |
| 'Charlie' | 'charlie@example.com' |

2 row(s) returned

Special Commands

LangDB supports several special commands:

  • .help - Display help information
  • .tables - List all tables in the database
  • .exit or .quit - Exit LangDB

Example:

langdb> .tables
Tables:
  users
  products
  orders

Common Operations

Creating Tables with Different Types

CREATE TABLE products (
    id INTEGER,
    name TEXT,
    price INTEGER,
    description TEXT NULL
);

Inserting with Specific Columns

INSERT INTO products (id, name, price) VALUES (1, 'Laptop', 1200);

Using WHERE Clauses

Supported operators: =, <>, !=, >, <, >=, <=

SELECT * FROM products WHERE price >= 1000;
SELECT name FROM products WHERE id = 1;
SELECT * FROM products WHERE name <> 'Laptop';

Working with NULL Values

INSERT INTO products VALUES (2, 'Phone', 800, NULL);
SELECT * FROM products WHERE description = NULL;

Multi-line SQL

You can write SQL statements across multiple lines. LangDB will wait for the semicolon:

langdb> SELECT id, name, price
....... FROM products
....... WHERE price > 500;

Example Session

Here's a complete example session:

-- Create a table
CREATE TABLE books (id INTEGER, title TEXT, author TEXT, year INTEGER);

-- Insert some books
INSERT INTO books VALUES 
    (1, 'The Rust Programming Language', 'Steve Klabnik', 2018),
    (2, 'Programming Rust', 'Jim Blandy', 2017),
    (3, 'Rust in Action', 'Tim McNamara', 2021);

-- Query all books
SELECT * FROM books;

-- Find recent books
SELECT title, year FROM books WHERE year >= 2020;

-- List all tables
.tables

-- Exit
.exit

Running SQL from a File

You can pipe SQL commands from a file:

./target/release/langdb < demo.sql

Or using cargo:

cargo run --release < demo.sql

Testing the Installation

Run the provided test script:

./test_run.sh

This will build the project and run a quick test to verify everything is working.

Next Steps

  • Read the full README.md for detailed documentation
  • Check out demo.sql for more examples
  • Review the CHANGELOG.md for version history
  • Explore the source code to understand the implementation

Troubleshooting

Build Errors

If you encounter build errors, make sure you have:

  • Rust 1.70 or later installed
  • Updated cargo: rustup update

Runtime Errors

  • Make sure SQL statements end with a semicolon (;)
  • Check that table names and column names are spelled correctly
  • Verify that data types match the schema

Getting Help

  • Use .help command in the REPL
  • Check the README.md for detailed documentation
  • Review error messages carefully - they usually indicate what went wrong

Have Fun!

LangDB is an educational project. Experiment with it, break it, and learn from it. Happy querying!