Snippet

Checking for Missing Data Using IS NULL Operator

In SQL, NULL represents a missing or unknown value. Because NULL cannot be evaluated using equality operators like '=', the special IS NULL operator must be used.

snippet.sql

sql

SELECT customer_id, email
FROM customers
WHERE phone_number IS NULL;

Breakdown

SELECT customer_id, email

Specifies the columns to retrieve in the query result.

FROM customers

Identifies 'customers' as the source table.

WHERE phone_number IS NULL;

Filters for records where the 'phone_number' field has no assigned value (is NULL).

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Checking for Missing Data Using IS NULL Operator

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