SelectQuery.class.php:

echo
    OSQL::select()->from('employer')->
    get('id')->get('name')->get('birth_date')->
    where(
        Expression::between(
            'birth_date',
            DBValue::create(1980),
            SQLFunction::create('now')
        )
    )->
        toString(
            DBFactory::getDefaultInstance()->getDialect()
        );

==

    SELECT "employer"."id", "employer"."name", "employer"."birth_date"
    FROM "employer"
    WHERE ("birth_date" BETWEEN '1980' AND now())

UpdateQuery.class.php:

    echo
        OSQL::update('imaginary_table')->
        set('field', 25)->
        set(
            'counter',
            Expression::add(
                DBField::create('counter'),
                1
            )
        )->
        setBoolean('boolean', true)->
        where(
            Expression::in(
                'id',
                OSQL::select()->from('update_queue')->
                    get('id')
            )
        )->
            toString(
                DBFactory::getDefaultInstance()->getDialect()
            );

==

    UPDATE "imaginary_table"
    SET
        "field"   = '25',
        "counter" = ("counter" + '1'),
        "boolean" = 'true'
    WHERE (
        "id" in (SELECT "update_queue"."id" FROM "update_queue")
    )

DeleteQuery.class.php:

echo
    OSQL::delete()->from('pity_table')->
    toString(
        DBFactory::getDefaultInstance()->getDialect()
    );

==

    Fatal error: Uncaught [leave 'pity_table' table alone in peace] in: ...