duckdb ~main

d-duckdb

DuckDB client for D. This client is based on DuckDB's C API.

Usage

Iterate query result via foreach

import duckdb;
import std;

void main()
{
    auto db = new Database(null);  // null for in-memory database
    auto conn = db.connect();

    writeln(duckdbVersion);

    conn.queryWithoutResult("CREATE TABLE integers (i INTEGER, j INTEGER);");
    conn.queryWithoutResult("INSERT INTO integers VALUES (3, 4), (5, 6), (7, NULL);");
    auto r = conn.query("SELECT * FROM integers;");
    foreach (int a, Nullable!int b; r)  // Specify argument types explicitly
        writeln(a, ", ",  b);

    conn.disconnect();
    db.close();
}

Prepared Statement

import duckdb;
import std;

void main()
{
    auto db = new Database(null);  // null for in-memory database
    auto conn = db.connect();

    writeln(duckdbVersion);

    conn.queryWithoutResult("CREATE TABLE integers (i SMALLINT, j BIGINT);");
    auto stmt1 = conn.prepare("INSERT INTO integers VALUES ($i,  $j)");

    foreach (i; 0..10) {
        short n1 = cast(short)i;
        long  n2 = long.max - i;
        stmt1.bindInt16(1, n1);
        stmt1.bindInt64(2, n2);
        stmt1.execute();
    }
    stmt1.destroy();

    auto stmt2 = conn.prepare("SELECT * FROM integers WHERE i BETWEEN ? AND ?;");
    stmt2.bindValues(3, 8);  // bindValues is shorter than calling each bindXXX
    foreach (short i, long j; stmt2.execute())
        writeln(i, " : ", j);
    stmt2.destroy();

    conn.disconnect();
    db.close();
}

Appender: Faster bulk insertion

import duckdb;
import std;

void main()
{
    auto db = new Database(null);  // null for in-memory database
    auto conn = db.connect();

    writeln(duckdbVersion);
    conn.queryWithoutResult("CREATE TABLE apps (i SMALLINT, str VARCHAR, ts TIMESTAMP);");
    auto appender = conn.appender("apps");
    foreach (i; 0..3)
        appender.appendRow(i, text("Name", i), Clock.currTime);
    appender.destroy();

    auto r = conn.query("SELECT * FROM apps;");
    foreach (short i, string str, SysTime ts; r)
        writeln("id: ", i, ", name: ", str, ", timestampe: ", ts);
    r.destroy();

    conn.disconnect();
    db.close();
}

DuckDB and D Types

Special cases

• NULL

Use std.typecons.Nullable to accept NULL for basic types, e.g. Nullable!int. Without Nullable, client returns .init value.

• Infinity for DATA and TIMESTAMP

Infinity/-Infinity is mapping to .init value, e.g. Date.init and SysTime.init.

TODO

• Support TODO DuckDB types
• Support more APIs
• Improve API design
• Add unittests

Links

• DuckDB – An in-process SQL OLAP database management system

DuckDB official site

• Overview – DuckDB

DuckDB C API document

Copyright

Copyright (c) 2024- Masahiro Nakagawa

License

Distributed under the Boost Software License, Version 1.0.