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.
Common causes of white plaques on the tongue. Leukoplakia. Leukoplakia is a common condition that results in a white patch in the mouth, which sometimes appears on the tongue. The patch is usually painless but cannot be removed by brushing or scraping.