# How the IsRing() function works in Mariadb?

The MariaDB `IsRing()`

function is used to assess whether a given `LINESTRING`

is a ring.

The MariaDB `IsRing()`

function is used to assess whether a given `LINESTRING`

is a ring. A ring is defined as a closed and simple curve, meaning it forms a complete loop without crossing itself.

## Syntax

MariaDB `IsRing()`

function’s syntax is as follows:

```
IsRing(g)
```

or

```
ST_IsRing(g)
```

Where `g`

is the `LINESTRING`

geometry to be tested. The function returns true if `g`

is both closed (its start and end points are coincident) and simple (the line does not intersect itself at any point).

## Examples

### Example 1: Simple Closed LineString

This example checks whether a closed `LINESTRING`

is a ring.

```
SELECT IsRing(ST_GeomFromText('LINESTRING(0 0, 1 1, 0 1, 0 0)'));
```

The output for this statement is:

```
+-----------------------------------------------------------+
| IsRing(ST_GeomFromText('LINESTRING(0 0, 1 1, 0 1, 0 0)')) |
+-----------------------------------------------------------+
| 1 |
+-----------------------------------------------------------+
```

This indicates that the `LINESTRING`

is a ring.

### Example 2: Non-Closed LineString

Here, we check a `LINESTRING`

that is not closed.

```
SELECT IsRing(ST_GeomFromText('LINESTRING(0 0, 1 1, 0 1)'));
```

The output for this statement is:

```
+------------------------------------------------------+
| IsRing(ST_GeomFromText('LINESTRING(0 0, 1 1, 0 1)')) |
+------------------------------------------------------+
| 0 |
+------------------------------------------------------+
```

This result confirms that the `LINESTRING`

is not a ring because it is not closed.

### Example 3: Self-Intersecting LineString

To demonstrate `IsRing()`

with a self-intersecting `LINESTRING`

.

```
SELECT IsRing(ST_GeomFromText('LINESTRING(0 0, 1 1, 1 0, 0 1, 0 0)'));
```

The output for this statement is:

```
+----------------------------------------------------------------+
| IsRing(ST_GeomFromText('LINESTRING(0 0, 1 1, 1 0, 0 1, 0 0)')) |
+----------------------------------------------------------------+
| 0 |
+----------------------------------------------------------------+
```

This shows that the `LINESTRING`

is not a ring because it intersects itself.

### Example 4: Valid Ring with Multiple Points

This example checks a valid ring with multiple defined points.

```
SELECT IsRing(ST_GeomFromText('LINESTRING(0 0, 2 0, 2 2, 0 2, 0 0)'));
```

The output for this statement is:

```
+----------------------------------------------------------------+
| IsRing(ST_GeomFromText('LINESTRING(0 0, 2 0, 2 2, 0 2, 0 0)')) |
+----------------------------------------------------------------+
| 1 |
+----------------------------------------------------------------+
```

This confirms that the `LINESTRING`

forms a valid ring.

### Example 5: LineString with Repeated Points

`IsRing()`

can also be used to check for repeated points in a `LINESTRING`

.

```
SELECT IsRing(ST_GeomFromText('LINESTRING(0 0, 1 1, 1 1, 0 0)'));
```

The output for this statement is:

```
+-----------------------------------------------------------+
| IsRing(ST_GeomFromText('LINESTRING(0 0, 1 1, 1 1, 0 0)')) |
+-----------------------------------------------------------+
| 1 |
+-----------------------------------------------------------+
```

This indicates that the `LINESTRING`

is not a ring because it has repeated points, violating the simplicity requirement.

## Related Functions

Below are a few functions related to MariaDB `IsRing()`

:

- MariaDB
`ST_IsClosed()`

function is used to determine if a`LINESTRING`

is closed. - MariaDB
`ST_IsSimple()`

function is used to determine if a geometry has no self-intersections. - MariaDB
`ST_GeometryType()`

function is used to return the geometry type of the input as a string.

## Conclusion

The `IsRing()`

function is an important tool in spatial analysis within MariaDB, allowing for the validation of `LINESTRING`

geometries as rings. Understanding how to use `IsRing()`

in conjunction with related functions can greatly enhance spatial data integrity and the accuracy of spatial operations. Ensuring that geometries meet the criteria of being both closed and simple is crucial for their correct usage in spatial computations.