A value of NULL indicates that the value is unknown. A value of NULL is different from an empty or zero value. No two null values are equal. Comparisons between two null values, or between a NULL and any other value, return unknown because the value of each NULL is unknown.
Skin Spots on the Face. Most causes of spots on face are harmless. They can be a variety of colors including white, red, black or brown. Common causes include cumulative sun exposure, acne, and skin tags. Keratoacanthoma (hyperkeratosis) is a lesion that grows rapidly, usually on areas exposed to the sun.
Human face, with left nasolabial fold marked in black ellipse. The nasolabial folds, commonly known as smile lines or laugh lines, are facial features. They are the two skin folds that run from each side of the nose to the corners of the mouth. They are defined by facial structures that support the buccal fat pad.