# Source: https://huggingface.co/docs/hub/datasets-duckdb-combine-and-export.md

# Combine datasets and export

In this section, we'll demonstrate how to combine two datasets and export the result. The first dataset is in CSV format, and the second dataset is in Parquet format. Let's start by examining our datasets:

The first will be [TheFusion21/PokemonCards](https://huggingface.co/datasets/TheFusion21/PokemonCards):

```bash
FROM 'hf://datasets/TheFusion21/PokemonCards/train.csv' LIMIT 3;
┌─────────┬──────────────────────┬─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬────────────┬───────┬─────────────────┐
│   id    │      image_url       │                                                                 caption                                                                 │    name    │  hp   │    set_name     │
│ varchar │       varchar        │                                                                 varchar                                                                 │  varchar   │ int64 │     varchar     │
├─────────┼──────────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼────────────┼───────┼─────────────────┤
│ pl3-1   │ https://images.pok…  │ A Basic, SP Pokemon Card of type Darkness with the title Absol G and 70 HP of rarity Rare Holo from the set Supreme Victors.  It has …  │ Absol G    │    70 │ Supreme Victors │
│ ex12-1  │ https://images.pok…  │ A Stage 1 Pokemon Card of type Colorless with the title Aerodactyl and 70 HP of rarity Rare Holo evolved from Mysterious Fossil from …  │ Aerodactyl │    70 │ Legend Maker    │
│ xy5-1   │ https://images.pok…  │ A Basic Pokemon Card of type Grass with the title Weedle and 50 HP of rarity Common from the set Primal Clash and the flavor text: It…  │ Weedle     │    50 │ Primal Clash    │
└─────────┴──────────────────────┴─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴────────────┴───────┴─────────────────┘
```

And the second one will be [wanghaofan/pokemon-wiki-captions](https://huggingface.co/datasets/wanghaofan/pokemon-wiki-captions):

```bash
FROM 'hf://datasets/wanghaofan/pokemon-wiki-captions/data/*.parquet' LIMIT 3;

┌──────────────────────┬───────────┬──────────┬──────────────────────────────────────────────────────────────┬────────────────────────────────────────────────────────────────────────────────────────────────────┐
│        image         │  name_en  │ name_zh  │                           text_en                            │                                              text_zh                                               │
│ struct(bytes blob,…  │  varchar  │ varchar  │                           varchar                            │                                              varchar                                               │
├──────────────────────┼───────────┼──────────┼──────────────────────────────────────────────────────────────┼────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ {'bytes': \x89PNG\…  │ abomasnow │ 暴雪王   │ Grass attributes,Blizzard King standing on two feet, with …  │ 草属性，双脚站立的暴雪王，全身白色的绒毛，淡紫色的眼睛，几缕长条装的毛皮盖着它的嘴巴               │
│ {'bytes': \x89PNG\…  │ abra      │ 凯西     │ Super power attributes, the whole body is yellow, the head…  │ 超能力属性，通体黄色，头部外形类似狐狸，尖尖鼻子，手和脚上都有三个指头，长尾巴末端带着一个褐色圆环 │
│ {'bytes': \x89PNG\…  │ absol     │ 阿勃梭鲁 │ Evil attribute, with white hair, blue-gray part without ha…  │ 恶属性，有白色毛发，没毛发的部分是蓝灰色，头右边类似弓的角，红色眼睛                               │
└──────────────────────┴───────────┴──────────┴──────────────────────────────────────────────────────────────┴────────────────────────────────────────────────────────────────────────────────────────────────────┘

```

Now, let's try to combine these two datasets by joining on the `name` column:

```bash
SELECT a.image_url
        , a.caption AS card_caption
        , a.name
        , a.hp
        , b.text_en as wiki_caption 
FROM 'hf://datasets/TheFusion21/PokemonCards/train.csv' a 
JOIN 'hf://datasets/wanghaofan/pokemon-wiki-captions/data/*.parquet' b 
ON LOWER(a.name) = b.name_en
LIMIT 3;

┌──────────────────────┬──────────────────────┬────────────┬───────┬──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│      image_url       │     card_caption     │    name    │  hp   │                                                                 wiki_caption                                                                 │
│       varchar        │       varchar        │  varchar   │ int64 │                                                                   varchar                                                                    │
├──────────────────────┼──────────────────────┼────────────┼───────┼──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ https://images.pok…  │ A Stage 1 Pokemon …  │ Aerodactyl │    70 │ A Pokémon with rock attributes, gray body, blue pupils, purple inner wings, two sharp claws on the wings, jagged teeth, and an arrow-like …  │
│ https://images.pok…  │ A Basic Pokemon Ca…  │ Weedle     │    50 │ Insect-like, caterpillar-like in appearance, with a khaki-yellow body, seven pairs of pink gastropods, a pink nose, a sharp poisonous need…  │
│ https://images.pok…  │ A Basic Pokemon Ca…  │ Caterpie   │    50 │ Insect attributes, caterpillar appearance, green back, white abdomen, Y-shaped red antennae on the head, yellow spindle-shaped tail, two p…  │
└──────────────────────┴──────────────────────┴────────────┴───────┴──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

```

We can export the result to a Parquet file using the `COPY` command:

```bash
COPY (SELECT a.image_url
        , a.caption AS card_caption
        , a.name
        , a.hp
        , b.text_en as wiki_caption 
FROM 'hf://datasets/TheFusion21/PokemonCards/train.csv' a 
JOIN 'hf://datasets/wanghaofan/pokemon-wiki-captions/data/*.parquet' b 
ON LOWER(a.name) = b.name_en) 
TO 'output.parquet' (FORMAT PARQUET);
```

Let's validate the new Parquet file:

```bash
SELECT COUNT(*) FROM 'output.parquet';

┌──────────────┐
│ count_star() │
│    int64     │
├──────────────┤
│         9460 │
└──────────────┘

```

> [!TIP]
> You can also export to [CSV](https://duckdb.org/docs/guides/file_formats/csv_export), [Excel](https://duckdb.org/docs/guides/file_formats/excel_export
> ) and [JSON](https://duckdb.org/docs/guides/file_formats/json_export
> ) formats.

Finally, let's push the resulting dataset to the Hub. You can use the Hub UI, the `huggingface_hub` client library and more to upload your Parquet file, see more information [here](./datasets-adding).

And that's it! You've successfully combined two datasets, exported the result, and uploaded it to the Hugging Face Hub.