database

A lightweight native MySQL/MariaDB & PostgreSQL driver written in D.

The goal is a native driver that re-uses the same buffers and the stack as much as possible, avoiding unnecessary allocations and work for the garbage collector

Native. No link, No harm :)

MySQL example

import std.datetime;
import std.stdio;
import mysql;

void main() {
    auto conn = new Connection("127.0.0.1", "root", "pwd", "test", 3306);

    // change database
    conn.use("mewmew");

    // simple insert statement
    conn.query("insert into users (name, email) values (?, ?)", "frank", "thetank@cowabanga.com");
    auto id = conn.lastInsertId;

    struct User {
        string name;
        string email;
    }

    // simple select statement
    User[] users;
    conn.query("select name, email from users where id > ?", 13, (MySQLRow row) {
        users ~= row.get!User;
    });

    // simple select statement
    conn.query("select name, email from users where id > ?", 13, (MySQLRow row) {
        writeln(row["name"], row["email"]);
    });

    // batch inserter - inserts in packets of 128k bytes
    auto insert = inserter(conn, "users_copy", "name", "email");
    foreach(user; users)
        insert.row(user.name, user.email);
    insert.flush;

    // re-usable prepared statements
    auto upd = conn.prepare("update users set sequence = ?, login_at = ?, secret = ? where id = ?");
    ubyte[] bytes = [0x4D, 0x49, 0x4C, 0x4B];
    foreach(i; 0..100)
        conn.exec(upd, i, Clock.currTime, MySQLBinary(bytes), i);

    // passing variable or large number of arguments
    string[] names;
    string[] emails;
    int[] ids = [1, 1, 3, 5, 8, 13];
    conn.query("select name from users where id in " ~ ids.placeholders, ids, (MySQLRow row) {
        writeln(row.name.peek!(char[])); // peek() avoids allocation - cannot use result outside delegate
        names ~= row.name.get!string;    // get() duplicates - safe to use result outside delegate
        emails ~= row.email.get!string;
    });

    // another query example
    conn.query("select id, name, email from users where id > ?", 13, (size_t index /*optional*/, MySQLHeader header /*optional*/, MySQLRow row) {
        writeln(header[0].name, ": ", row.id.get!int);
        return (index < 5); // optionally return false to discard remaining results
    });

    // structured row
    conn.query("select name, email from users where length(name) > ?", 5, (MySQLRow row) {
        auto user = row.get!User; // default is strict.yesIgnoreNull - a missing field in the row will throw
        // auto user = row.get!(User, Strict.yes); // missing or null will throw
        // auto user = row.get!(User, Strict.no);  // missing or null will just be ignored
        writeln(user);
    });

    // structured row with nested structs
    struct GeoRef {
        double lat;
        double lng;
    }

    struct Place {
        string name;
        GeoRef location;
    }

    conn.query("select name, lat as `location.lat`, lng as `location.lng` from places", (MySQLRow row) {
        auto place = row.get!Place;
        writeln(place.location);
    });

    // structured row annotations
    struct PlaceFull {
        uint id;
        string name;
        @optional string thumbnail;    // ok to be null or missing
        @optional GeoRef location;     // nested fields ok to be null or missing
        @optional @as("contact_person") string contact; // optional, and sourced from field contact_person instead

        @ignore File tumbnail;    // completely ignored
    }

    conn.query("select id, name, thumbnail, lat as `location.lat`, lng as `location.lng`, contact_person from places", (MySQLRow row) {
        auto place = row.get!PlaceFull;
        writeln(place.location);
    });


    // automated struct member uncamelcase
    struct PlaceOwner {
    @snakeCase:
        uint placeID;            // matches placeID and place_id
        uint locationId;         // matches locationId and location_id
        string ownerFirstName;   // matches ownerFirstName and owner_first_name
        string ownerLastName;    // matches ownerLastName and owner_last_name
        string feedURL;          // matches feedURL and feed_url
    }

    conn.close();
}

PGSQL example

import std.stdio;
import postgresql;

@snakeCase struct PlaceOwner {
@snakeCase:
    @sqlkey() uint placeID; // matches place_id
    uint locationId; // matches location_id
    string ownerName; // matches owner_name
    string feedURL; // matches feed_url
}

auto db = PgSQLDB("127.0.0.1", "postgres", "postgres", "postgres");
db.runSql(`CREATE TABLE IF NOT EXISTS company(
ID INT PRIMARY KEY	NOT NULL,
NAME		TEXT	NOT NULL,
AGE			INT		NOT NULL,
ADDRESS		CHAR(50),
SALARY		REAL,
JOIN_DATE	DATE
);`);
assert(db.hasTable("company"));
assert(db.query("select 42").get!int == 42);
db.create!PlaceOwner;
db.insert(PlaceOwner(1, 1, "foo", ""));
db.insert(PlaceOwner(2, 1, "bar", ""));
db.insert(PlaceOwner(3, 3, "baz", ""));
auto s = db.selectOneWhere!(PlaceOwner, "owner_name=$1")("bar");
assert(s.placeID == 2);
assert(s.ownerName == "bar");
foreach (row; db.selectAllWhere!(PlaceOwner, "location_id=$1")(1))
    writeln(row);
db.exec("drop table place_owner");
db.exec("drop table company");
db.close();

SQLite example

import database.sqlite.db;

auto db = SQLite3DB("file.db");
db.exec("INSERT INTO user (name, id) VALUES (?, ?)", name, id);

struct User {
    ulong id;
    string name;
    void[] pixels;
};

User[] users;
auto q = db.query("SELECT id,name FROM user");
while(q.step()) {
    users ~= q.get!User;
}