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 the white patches on your tongue. 2  Leukoplakia can develop when your tongue has been irritated and is often found in people who use tobacco products. 3  Oral thrush. 4  Also known as candidiasis, oral thrush is a yeast infection that develops inside the mouth.here are a number of things that can cause a whitish coating or white spots to develop on the tongue, including the f ollowing: 1  Leukoplakia. 2  This condition causes cells in the mouth to grow excessively.