# COLUMN\_ADD

## Syntax

```sql
COLUMN_ADD(dyncol_blob, column_nr, value [as type], [column_nr, value [as type]]...)
COLUMN_ADD(dyncol_blob, column_name, value [as type], [column_name, value [as type]]...)
```

## Description

Adds or updates [dynamic columns](https://mariadb.com/docs/server/reference/sql-structure/nosql/dynamic-columns).

* `dyncol_blob` must be either a valid dynamic columns blob (for example, `COLUMN_CREATE` returns such blob), or an empty string.
* `column_name` specifies the name of the column to be added. If `dyncol_blob` already has a column with this name, it will be overwritten.
* `value` specifies the new value for the column. Passing a NULL value will cause the column to be deleted.
* `as type` is optional. See [#datatypes](#datatypes) section for a discussion about types.

The return value is a dynamic column blob after the modifications.

## Examples

```sql
UPDATE t1 SET dyncol_blob=COLUMN_ADD(dyncol_blob, "column_name", "value") WHERE id=1;
```

Note: `COLUMN_ADD()` is a regular function (just like [CONCAT()](https://mariadb.com/docs/server/reference/sql-functions/string-functions/concat)), hence, in order to update the value in the table you have to use the `UPDATE ... SET dynamic_col=COLUMN_ADD(dynamic_col, ....)` pattern.

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