gistfile1.sql

        WITH
        update_graphics_device AS (
            UPDATE graphics_device
            SET
                adapter_name = 'Unknown Webcam Pro 9000',
                vendor_name = 'Logitech Inc.'
            WHERE
                vendor_hex = '0x1002'
                AND
                adapter_hex = '0x0166'
            RETURNING 1
        ),
        insert_graphics_device AS (
            INSERT INTO
                graphics_device
                (vendor_hex, adapter_hex, vendor_name, adapter_name)
            SELECT
                '0x1002' AS vendor_hex,
                '0x0166' AS adapter_hex,
                'Logitech Inc.' AS vendor_name,
                'Unknown Webcam Pro 9000' AS adapter_name
            WHERE NOT EXISTS (
                SELECT * FROM graphics_device
                WHERE
                    vendor_hex = '0x1002'
                    AND
                    adapter_hex = '0x0166'
                LIMIT 1
            )
            RETURNING 2
        )
        SELECT * FROM update_graphics_device UNION ALL SELECT * FROM insert_graphics_device;