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.
Discoloration of the tongue can be from many causes-often the color of a liquid or food. It is often caused by yeast also. When some one is on antibiotics the oral flora changes - bacteria is less, yeast increase; bacteria can also cause color changes. Some diseases, variants may cause changes.