Working With NULLs

Nulls are database fields that do not contain a value. It is important to understand how nulls are represented in the Campaign Manager system, and how they can be used in queries.

For example, in the following data helper there are 34,946 records that do not have a value for the field Income Numeric. These are the nulls. This does not include people that have an income of zero ('0)' who would be included in the 10K under segment.

Representing NULLs

Data helpers display nulls with the value label null in italics to differentiate from any engineered columns that include the text string NULL (never italicized).

Querying NULLs

When incorporating nulls into a query, use the operators Is Null and Is Not Null. For example:

The following is NOT CORRECT and will not return null values but will instead return fields that contain the text string 'NULL'.

In NSQL the query format would be Select * from [Table] where [Column] IS NULL.

When dragging the null segment from a data helper to a segment document, the query element will also be represented as IS NULL. The Null segment cannot be used in conjunction with any other operator, for example it is not valid to say: Give me all values greater than NULL. In this case you would use Is Not Null to achieve the desired results. It is also not valid to include a null in an IN statement.

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