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.
Skin conditions. Certain skin conditions may cause tongue inflammation. Oral lichen planus is an inflammatory disease causing sores, swelling, and redness. Syphilis is a sexually transmitted infection that can present as a body rash. Pemphigus is an autoimmune disease that causes skin blistering.