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.
Causes of coated tongue vary. The difference in the tongue coating appearance can help narrow down the causes and treatments. White Tongue The tongue appears to have a thick, white coating due to inflammation and trapped particles, such as dead cells and bacteria. The causes of a white tongue coating are varied. Usually, white tongue poses little concern and may be caused by dehydration, mouth breathing, medications, alcohol use, smoking, or fever.