​Which Comparison Operator Allows You to Search for NULL Values

question 123

Multiple Choice

​Which comparison operator allows you to search for NULL values in a subquery?

• A) ​IS NULL
• B) ​NVL
• C) ​=NULL
• D) ​NVLS

---

Definitions:

Allergist

An allergist is a medical professional specializing in the diagnosis and treatment of allergic conditions and immune system disorders.

Electroencephalography

A non-invasive method to record electrical activity of the brain using electrodes placed on the scalp.

Electrocardiography

The process of recording the electrical activity of the heart over a period of time using electrodes placed on the skin.

Electromyography

A procedure in which needle electrodes are inserted into some of the skeletal muscles and a monitor records the nerve impulses and measures conduction time; used to detect neuromuscular disorders or nerve damage.