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.
What causes a white tongue? Here are eight causes of a white tongue ranging in severity. Leukoplakia: This condition is caused by a high production of cells in the mouth as well as deposits of keratin. White spots can appear on the tongue, gums, and inner mouth.