NULL

Indicates that a value is either unknown or undefined. NULL is not equivalent to a blank or empty string (for character columns) or 0 (for numerical columns).

Although you can write expressions that return nulls, any column that has the NOT NULL or PRIMARY KEY constraint will not accept nulls. Therefore, if Informatica Cloud tries to write a null value to a column with one of these constraints, the database will reject the row and Informatica Cloud will write it to the reject file. Be sure to consider nulls when you create transformations.

Functions can handle nulls differently. If you pass a null value to a function, it might return 0 or NULL, or it might ignore null values.

Expressions that combine a null value with a Boolean expression produces results that are ANSI compliant. For example:

If a filter condition evaluates to NULL, the function does not select the record.

Any expression that uses operators (except the string operator ||) and contains a null value always evaluates to NULL. For example, the following expression evaluates to NULL:

To test for nulls, use the ISNULL function.