tinydb

A tiny and dummy database built by myself.

Introduction

This project is inspired by sqlite, has a similar architecture with sqlite (but simpler).

• tinydb is the simplest prototype of database, it only contains ONE table (see table_t and row_t in source file types.h), whose schema is id(uint32_t), username(string), email(string) .
• id(int) is the primary key of our table, we will implement index via B+Tree.
• sqlparser-main.c - The entry of tinydb. In this program, I implement an tiny SQL Parser based on Flex & Bison, thus the SQL statements in this program are mostly like sqlite or MySQL. And it supports where conditions.

Build sqlparser-main.c

make build
./tinydb mydb.db

In this program, I implement a SQL Parser. It will support SQL statements like:

• SELECT * FROM table;
• SELECT col1, col2 FROM table;
• SELECT * FROM table WHERE conditions;
• SELECT col1, col2 FROM table WHERE conditions;
• INSERT INTO table VALUES (NUMBER, STRING, STRING);
• DELETE FROM table WHERE conditions;
• UPDATE table SET col1 = val1, col2 = val2;
• COMMIT;
• ROLLBACK;

For the above keywords, they can be lower cases: select, insert, delete, update, ...

Please note that there is a ';' after each SQL statement.

And the conditions support operators: =, !=, >=, >, <=, <, AND, OR, e.g.

SELECT * FROM table WHERE id < 10 OR id > 100 AND username = 'sinkinben';
SELECT * FROM table WHERE id = 1 AND username='1' OR id >= 10 AND id < 20;
SELECT * FROM table WHERE id = 1 AND username='1' OR id >= 10 AND username < '20';

The keywords AND, OR can be and, or.

Here is an example, showing how to use tinydb.

tinydb > insert into table values (1, 'sinkinben', 'skb@qq.com');
Executed.
tinydb > select * from table where id=1 and username='sinkinben';
id = 1 username = sinkinben email = skb@qq.com
total 1 rows
Executed.
tinydb > update table set email='sinkinben@outlook.com' where id=1;
Executed.
tinydb > select * from table;
(1, sinkinben, sinkinben@outlook.com)
total 1 rows
Executed.
tinydb > .exit

Running Test

mv gemfile Gemfile  # rename Gemfile
bundle install
bundle exec rspec

Running this testing script, will fill the database file mydb.db with dummy data (total 6000 rows).

Further Reading

• [1] SQLite Database System: Design and Implementation
• [2] Architecture of SQLite
• [3] https://github.com/cstack/db_tutorial