SQLite Clone In C

A study of how a database works by implementing one.

The database now has the following functions:

Select all Rows
Insert a Row
Create a table
Get table information

The code aims to be readable, so to undestand the code, you can start by reading the main.c file.

Right now the implementation supports one row per file. The table and its information is persisted in a file that is passed to the program as an argument.

File Architecture

The persistence of the database is done by writing the table information in a file. The file has a header in the start of the file, then the header is structured as follows:

header_size: size_t
col_count: uint8_t
table_name_size: size_t
table_name: char[table_name_size]
# For each Column
...
col_type: uint8_t
col_name_size: size_t
col_name: char[col_name_size]
...

The rest of the file consists of the rows of the table. That are saved one in order.

Queries

CREATE TABLE <table_name> (<column_name>:<column_type>, ...): Creates a table with the given name and column. The column type can be REAL, TEXT and INTEGER. The ID column is automatically created in the table.
INSERT (<value>, ...): Inserts a row with the given values. The program checks the number of values and the types of the columns to insert the row.
SELECT: Selects all rows from the table.

Metacommands

.exit: Exits and saves the program.
.info: Shows the table information.
.help: Shows the help message.

How to run

To run the program, you need to have the gcc compiler and make installed. Then, you can run the following commands:

make run

How to run integration tests

To run the tests, you need to install:

Ruby
bundle

Then, you can run the following commands:

make rspec

TODO

Implement the B-Tree
Implement the Schema Table, so that more tables can be stored in a single file
Rust API to use the database
Implement the DELETE query
Implement the SELECT options, like WHERE, ORDER BY, LIMIT
Implement the UPDATE query
Implement the INSERT query with the column names
Implement better String representation