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.

Operator operand

Binary operators operate on two operands. There are also some special operators for operations on more than two operators.

Operator operand,operand

**UNION**- all non-duplicated results from the union of two queries.**UNION ALL**- all results from the union of two queries regardless of duplication.**INTERSECT**- common results only from two queries.**MINUS**- non-common results only from two queries.

The AND logical operator and the equals (*=*) operators are the most frequently used.

**=**- equality.**!=**- inequality.**~=**- inequality.**<>**- inequality.**>**- greater than.**<**- less than.**>=**- greater than or equal to.**<=**- less than or equal to.**IN**- in a set.**NOT IN**- not in a set.**ANY SOME**- compares a value to each value in a list returned from a query, FALSE if no rows returned.**ALL**- a value must relate to the entire list or the subquery as indicated.**[NOT] BETWEEN**- inclusion between*x*AND*y**x*and*y*inclusive of both.**EXISTS TRUE**- subquery returns atleast a single row.-*x*[NOT] LIKE*y*[ESCAPE 'z'] TRUE*x*matching the pattern*y*.*y*can contain wildcard characters*%*and*_*. Any non-wildcard character can follow ESCAPE to allow for matching of restricted characters such as wildcard characters.Like 'G%VIN' matches 'G ... VIN'. % = matches 0 or more characters. _ - matches exactly one character.

**IS [NOT] NULL**- tests for NULL values.