> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-vortex-format.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Documentation for the ODBCDriver2 format

# ODBCDriver2

| Input | Output | Alias |
| ----- | ------ | ----- |
| ✗     | ✔      |       |

<h2 id="description">
  Description
</h2>

The `ODBCDriver2` format is a binary, output-only format used to transfer query results over HTTP to the
[ClickHouse driver for `ODBC`](/concepts/features/interfaces/odbc). The driver requests it by setting `default_format` to
`ODBCDriver2`; users normally don't select it directly.

All integers in the stream are signed 32-bit values encoded in little-endian byte order. A string is encoded as its byte
length followed by its bytes. The output has the following structure:

1. The value `2`, indicating that two header rows follow.
2. A names header containing the value `number_of_columns + 1`, the string `name`, and each column name.
3. A types header containing the value `number_of_columns + 1`, the string `type`, and each ClickHouse data type name.
   `LowCardinality` wrappers are removed from these type names.
4. The data rows. Each row contains one text-serialized, length-prefixed value for every result column. Data rows don't
   include their own row or column count, and the stream ends at `EOF`.

A `NULL` value is encoded with the length `-1`; an empty non-null string has length `0`. Totals, when present, use the
same row encoding and follow the ordinary rows.

<h2 id="example-usage">
  Example usage
</h2>

The following query is representative of the values covered by the format's tests:

```sql theme={null}
SELECT
    1 AS x,
    [2, 3] AS y,
    'Hello' AS z,
    NULL AS a
FORMAT ODBCDriver2
```

Because the result is binary, direct it to a file rather than a terminal:

```shell theme={null}
clickhouse-client --query \
    "SELECT 1 AS x, [2, 3] AS y, 'Hello' AS z, NULL AS a FORMAT ODBCDriver2" \
    > result.bin
```

In normal use, the driver adds `default_format=ODBCDriver2` to its HTTP requests and decodes the response.

<h2 id="format-settings">
  Format settings
</h2>

`ODBCDriver2` uses the standard text-serialization settings for individual values. It has no settings specific to the
format itself.