# BSON\_UNWIND

Converts a BSON document to a PSQL array.

## Syntax

```
BSON_UNWIND(<input>)
```

## Argument

`<input>`: A valid BSON type or array, or an expression that evaluates to a valid BSON type or array.

## Return Type

A PSQL array.

## Remarks

* If the input is a valid non-empty BSON array, a PSQL array is returned.
* If the input is a BSON type other than the array, it is mapped to the PSQL array as a single element.
* `BSON_UNWIND()` returns `NULL` if the input is a SQL `NULL`, BSON `NULL`, BSON `undefined`, or an empty BSON array.

## Examples

**Note**: The following examples explicitly cast string to BSON for clarity. Similarly, the output is cast to JSON. The `TABLE()` command is used to convert the PSQL array to a set of rows.

The following example adds the BSON input as a single element in the array because the input is not a BSON array.

```sql
SELECT table_col:>JSON AS Result
FROM TABLE(BSON_UNWIND('{"field1":"string value","field2":[12,3,1331,"arr"],"field3":true,"field4":null}':>BSON));

```

```output

+----------------------------------------------------------------------------------+
| Result                                                                           |
+----------------------------------------------------------------------------------+
| {"field1":"string value","field2":[12,3,1331,"arr"],"field3":true,"field4":null} |
+----------------------------------------------------------------------------------+
```

The following example converts a BSON array to a PSQL array and returns the result as a set of rows, where each row represents an element in the array.

```sql
SELECT table_col:>JSON AS Result FROM TABLE(BSON_UNWIND('[1,true,null,"a string",2,3,4,5,{"a":"abc","b":[]},{}]':>BSON));

```

```output

+--------------------+
| Result             |
+--------------------+
| 1                  |
| true               |
| null               |
| "a string"         |
| 2                  |
| 3                  |
| 4                  |
| 5                  |
| {"a":"abc","b":[]} |
| {}                 |
+--------------------+
```

***

Modified at: May 8, 2024

Source: [/db/v9.1/reference/sql-reference/bson-functions/bson-unwind/](https://docs.singlestore.com/db/v9.1/reference/sql-reference/bson-functions/bson-unwind/)

(An index of the documentation is available at /llms.txt)