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.
Tinea versicolor is a common fungal infection of the skin in adolescents and young adults and leads to discolored patches of skin, usually pale (hypopigmented) spots on the upper back and shoulders. It is caused by a yeast (Malassezia furfur), which produces a substance that suppresses color production in the skin, leading to the pale spots.