# DISTINCT

`DISTINCT` removes duplicate rows from the projected query result. It applies to all selected expressions together, rather than to one column independently.

For duplicate elimination, `NULL` is equal to another `NULL`. Text equality follows the expression's collation. `DISTINCT ON` is not supported.

## Syntax

```text
SELECT DISTINCT expression [, ...]
FROM source
```

## Examples

### Unique combinations

The same country can occur more than once when the complete projected rows differ:

```sql
CREATE TABLE visits (country TEXT, device TEXT);
INSERT INTO visits VALUES ('GB', 'desktop'), ('GB', 'desktop'), ('GB', 'mobile'), ('FR', 'mobile');
```

```sql
SELECT DISTINCT country, device
FROM visits
ORDER BY country, device
FORMAT csv;
```

```text
"FR","mobile"
"GB","desktop"
"GB","mobile"
```

### Duplicate NULL values

```sql
CREATE TABLE readings (value INTEGER);
INSERT INTO readings VALUES (1), (1), (NULL), (NULL);
```

```sql
SELECT DISTINCT value
FROM readings
ORDER BY value
FORMAT csv;
```

```text
\N
1
```

For a count of unique non-`NULL` values, use [`count(DISTINCT value)`](https://coordinatordb.com/docs/reference/functions/aggregate-functions/count).