An operator given a NULL value other than the concatenation operator (||) has a result of NULL. There are a number of types of operators. Operator precedence is the order of evaluation. In general precedence is evaluated from left to right. Parentheses (( ... )) will override precedence. Parentheses contents are always evaluated first. More specifically precedence is governed as in the table shown below.
|* and /|
|+ and -|
|Binary (=) and concatenation (||)|
|All comparison operators including NOT, AND and OR|
Unary operators operate on a single operand.
Binary operators operate on two operands. There are also some special operators for operations on more than two operators.
Operator operand, operand
The AND logical operator and the equals (=) operators are the most frequently used.
Like 'G%VIN' matches 'G ... VIN'. % = matches 0 or more characters. _ - matches exactly one character.