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.
1 So it is important for your dentist to determine the cause of white patches on your tongue. Leukoplakia can develop when the tongue has been irritated, and it is often found in people who use tobacco products.  Oral thrush . Also known as candidiasis, oral thrush is a yeast infection that develops inside the mouth. The condition results in white patches that are often cottage cheese-like in consistency on the surfaces of the mouth and tongue.