The SQL NULL is the term used to represent a missing value. A NULL value in a table is a value in a field that appears to be blank. A field with a NULL value is a field with no value. It is very important to understand that a NULL value is different than a zero value or a field that contains spaces.
Someone with red spots on their tongue may be suffering from geographic tongue, according to Mayo Clinic. Other causes of red spots on the tongue include folic acid and vitamin B-12 deficiencies and scarlet fever, WebMD states. Continue Reading.
Q: What causes geographic tongue? A: The cause of geographic tongue is unknown. Several factors have been proposed as possible causes such as emotional stress, psychological factors, habits, allergies, diabetes and hormonal disturbances. However, none of these factors have been conclusively linked to geographic tongue. A relationship between geographic tongue and psoriasis (a skin disease) has been reported.