# Check Whether Related Data Exists by Using Subqueries

To check for the presence or absence of related data, use the `EXISTS` or `NOT EXISTS` operators. These operators are part of the `WHERE` clause that precedes a subquery. A subquery is a query that appears inside another query statement.

These query examples all use a subquery to check on related records to accounts.

- Which accounts don’t have a phone number?
- Which accounts have a phone number but no email address?
- How many accounts have a phone number but no email address?

For example, this query uses a subquery to return the accounts that don’t have a phone number.

```
SELECT "ssot__Id__c",
       "ssot__Name__c"
FROM "ssot__Account__dlm"
WHERE NOT EXISTS (
 SELECT *
      FROM "ssot__ContactPointPhone__dlm"
 WHERE "ssot__ContactPointPhone__dlm"."ssot__PartyId__c" = "ssot__Account__dlm"."ssot__Id__c"
)

```

This output shows the first few rows of the sample results.

| `ssot__Id__c`      | `ssot__Name__c`             |
| ------------------ | --------------------------- |
| 001Hu00002xHZJnIAO | Pyramid Construction Inc.   |
| 001Hu00002xHZJtIAO | United Oil & Gas, UK        |
| 001Hu00002xHZJuIAO | United Oil & Gas, Singapore |

You can use these predicates with subqueries.

- `EXISTS`
- `NOT EXISTS`
- `IN`