> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/reference/sql-statements/geometry-constructors/geometry-constructors/st_union.md).

# ST\_UNION

## Syntax

```bnf
ST_UNION(g1,g2)
```

## Description

Returns a geometry that is the union of the geometry *`g1`* and geometry *`g2`*.

## Examples

```sql
SET @g1 = GEOMFROMTEXT('POINT (0 2)');

SET @g2 = GEOMFROMTEXT('POINT (2 0)');

SELECT ASTEXT(ST_UNION(@g1,@g2));
+---------------------------+
| ASTEXT(ST_UNION(@g1,@g2)) |
+---------------------------+
| MULTIPOINT(2 0,0 2)       |
+---------------------------+
```

```sql
SET @g1 = GEOMFROMTEXT('POLYGON((0 0,0 3,3 3,3 0,0 0))');

SET @g2 = GEOMFROMTEXT('POLYGON((2 2,4 2,4 4,2 4,2 2))');

SELECT ASTEXT(ST_UNION(@g1,@g2));
+------------------------------------------------+
| ASTEXT(ST_UNION(@g1,@g2))                      |
+------------------------------------------------+
| POLYGON((0 0,0 3,2 3,2 4,4 4,4 2,3 2,3 0,0 0)) |
+------------------------------------------------+
```

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