# JSON\_OBJECTAGG

{% hint style="info" %}
`JSON_OBJECTAGG` is available from MariaDB 10.5.
{% endhint %}

## Syntax

```sql
JSON_OBJECTAGG(key, value)
```

## Description

`JSON_OBJECTAGG` returns a JSON object containing key-value pairs. It takes two expressions that evaluate to a single value, or two column names, as arguments, the first used as a key, and the second as a value.

The maximum returned length in bytes is determined by the [group\_concat\_max\_len](https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#group_concat_max_len) server system variable.

Returns `NULL` in the case of an error, or if the result contains no rows.

`JSON_OBJECTAGG` cannot currently be used as a [window function](https://mariadb.com/docs/server/reference/sql-functions/special-functions/window-functions).

## Examples

```sql
SELECT * FROM t1;
+------+-------+
| a    | b     |
+------+-------+
|    1 | Hello |
|    1 | World |
|    2 | This  |
+------+-------+

SELECT JSON_OBJECTAGG(a, b) FROM t1;
+----------------------------------------+
| JSON_OBJECTAGG(a, b)                   |
+----------------------------------------+
| {"1":"Hello", "1":"World", "2":"This"} |
+----------------------------------------+
```

<sub>*This page is licensed: CC BY-SA / Gnu FDL*</sub>

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