Amazon Redshift will no longer support the creation of new Python UDFs starting Patch 198. Existing Python UDFs will continue to function until June 30, 2026. For more information, see the [ blog post ](https://aws.amazon.com/blogs/big-data/amazon-redshift-python-user-defined-functions-will-reach-end-of-support-after-june-30-2026/). 

# EXISTS condition
<a name="r_exists_condition"></a>

EXISTS conditions test for the existence of rows in a subquery, and return true if a subquery returns at least one row. If NOT is specified, the condition returns true if a subquery returns no rows.

## Syntax
<a name="r_exists_condition-synopsis"></a>

```
[ NOT ] EXISTS (table_subquery)
```

## Arguments
<a name="r_exists_condition-arguments"></a>

 EXISTS   
Is true when the *table\$1subquery* returns at least one row.

NOT EXISTS   
Is true when the *table\$1subquery* returns no rows.

 *table\$1subquery*   
A subquery that evaluates to a table with one or more columns and one or more rows.

## Example
<a name="r_exists_condition-example"></a>

This example returns all date identifiers, one time each, for each date that had a sale of any kind:

```
select dateid from date
where exists (
select 1 from sales
where date.dateid = sales.dateid
)
order by dateid;

dateid
--------
1827
1828
1829
...
```