sqlight

Use SQLite from Gleam!

Works on Erlang and on JavaScript runtimes that support node:sqlite, like NodeJS, and NodeJS.

gleam add sqlight

import gleam/dynamic/decode
import sqlight

pub fn main() {
  use conn <- sqlight.with_connection(":memory:")

  let sql = "
  create table cats (name text, age int);

  insert into cats (name, age) values 
  ('Nubi', 4),
  ('Biffy', 10),
  ('Ginny', 6);
  "
  let assert Ok(Nil) = sqlight.exec(sql, conn)

  let cat_decoder = {
    use name <- decode.field(0, decode.string)
    use age <- decode.field(1, decode.int)
    decode.success(#(name, age))
  }

  let sql = "
  select name, age from cats
  where age < ?
  "
  let assert Ok([#("Nubi", 4), #("Ginny", 6)]) =
    sqlight.query(sql, on: conn, with: [sqlight.int(7)], expecting: cat_decoder)
}

Documentation can be found at https://hexdocs.pm/sqlight.

Why SQLite?

SQLite is a implementation of SQL as a library. This means that you don't run a separate SQL server that your program communicates with, but you embed the SQL implementation directly in your program. SQLite stores its data in a single file. The file format is portable between different machine architectures. It supports atomic transactions and it is possible to access the file by multiple processes and different programs.

You can also use in-memory databases with SQLite, which may be useful for testing.

Implementation

When running on Erlang it is a library wrapper around the excellent Erlang library esqlite, which in turn is a wrapper around the SQLite C library. It is implemented as a NIF, which means that the SQLite database engine is linked to the erlang virtual machine.

When running on JavaScript it is a wrapper around the node:sqlite module that is built-in to the most common runtimes.

On using Bool with SQLite

SQLite does not have a native boolean type. Instead, it uses ints, where 0 is False and 1 is True. Because of this the Gleam stdlib decoder for bools will not work, instead the sqlight.decode_bool function should be used as it supports both ints and bools.