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.
Median rhomboid glossitis is a condition that can affect your tongue if you have oral thrush. It causes a red, smooth patch or lump to develop in the middle of the top part of your tongue, which can be sore. You're more likely to develop oral thrush if you: have recently taken antibiotics.
A black hairy tongue is caused by too much bacteria or yeast growth in the mouth. The bacteria build up on tiny rounded projections called papillae.ut the tongue can also turn brown, yellow, green, or a variety of other colors. Certain lifestyle habits and conditions can make people more likely to develop black hairy tongue. They include: 1  poor oral hygiene. 2  smoking tobacco.