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# Sqlitex
An Elixir wrapper around [esqlite](https://github.com/mmzeeman/esqlite). The main aim here is to provide convenient usage of SQLite databases.
# Updated to 1.0
With the 1.0 release, we made just a single breaking change. `Sqlitex.Query.query` previously returned just the raw query results on success and `{:error, reason}` on failure.
This has been bothering us for a while, so we changed it in 1.0 to return `{:ok, results}` on success and `{:error, reason}` on failure.
This should make it easier to pattern match on. The `Sqlitex.Query.query!` function has kept its same functionality of returning bare results on success and raising an error on failure.
# Usage
The simple way to use `sqlitex` is just to open a database and run a query:
```elixir
Sqlitex.with_db('test/fixtures/golfscores.sqlite3', fn(db) ->
Sqlitex.query(db, "SELECT * FROM players ORDER BY id LIMIT 1")
end)
# => [[id: 1, name: "Mikey", created_at: {{2012,10,14},{05,46,28}}, updated_at: {{2013,09,06},{22,29,36}}, type: nil]]
Sqlitex.with_db('test/fixtures/golfscores.sqlite3', fn(db) ->
Sqlitex.query(db, "SELECT * FROM players ORDER BY id LIMIT 1", into: %{})
end)
# => [%{id: 1, name: "Mikey", created_at: {{2012,10,14},{05,46,28}}, updated_at: {{2013,09,06},{22,29,36}}, type: nil}]
```
Pass the `bind` option to bind parameterized queries.
```elixir
Sqlitex.with_db('test/fixtures/golfscores.sqlite3', fn(db) ->
Sqlitex.query(
db,
"INSERT INTO players (name, created_at, updated_at) VALUES (?1, ?2, ?3, ?4)",
bind: ['Mikey', '2012-10-14 05:46:28.318107', '2013-09-06 22:29:36.610911']
)
end)
# => [[id: 1, name: "Mikey", created_at: {{2012,10,14},{05,46,28}}, updated_at: {{2013,09,06},{22,29,36}}, type: nil]]
```
If you want to keep the database open during the lifetime of your project, you can use the `Sqlitex.Server` GenServer module.
Here's a sample from a phoenix projects main supervisor definition.
```elixir
children = [
# Start the endpoint when the application starts
worker(Golf.Endpoint, []),
worker(Sqlitex.Server, ['golf.sqlite3', [name: Golf.DB]])
]
```
Now that the GenServer is running you can make queries via
```elixir
Sqlitex.Server.query(Golf.DB,
"SELECT g.id, g.course_id, g.played_at, c.name AS course
FROM games AS g
INNER JOIN courses AS c ON g.course_id = c.id
ORDER BY g.played_at DESC LIMIT 10")
```
# Configuration
Sqlitex uses the Erlang library [esqlite](https://github.com/mmzeeman/esqlite)
which accepts a timeout parameter for almost all interactions with the database.
The default value for this timeout is 5000 ms. Many functions in Sqlitex accept
a `:db_timeout` option that is passed on to the esqlite calls and also defaults
to 5000 ms. If required, this default value can be overridden globally with the
following in your `config.exs`:
```
config :sqlitex, db_timeout: 10_000 # or other positive integer number of ms
```
Another esqlite parameter is :db_chunk_size.
This is a count of rows to read from native sqlite and send to erlang process in one bulk.
For example, the table `mytable` has 1000 rows. We make the query to get all rows with `db_chunk_size: 500` parameter:
```
Sqlitex.query(db, "select * from mytable", db_chunk_size: 500)
```
in this case all rows will be passed from native sqlite OS thread to the erlang process in two passes.
Each pass will contain 500 rows.
This parameter decrease overhead of transmitting rows from native OS sqlite thread to the erlang process by
chunking list of result rows.
Please, decrease this value if rows are heavy. Default value is 5000.
If you in doubt what to do with this parameter, please, do nothing. Default value is ok.
```
config :sqlitex, db_chunk_size: 500 # if most of the database rows are heavy
```
# Looking for Ecto?
Check out the [SQLite Ecto2 adapter](https://github.com/Sqlite-Ecto/sqlite_ecto2)
