# Boolean operator

The 16 Boolean operators with 2 variables

A Boolean operator ( English Boolean operator ) is a logical operator so an operator which in truth values operated on. It is named after George Boole . The most important application area of ​​the Boolean operators is programming . A mathematical specification of the theory of Boolean operators was formalized in the concept of Boolean algebra . There the Boolean operator acts as a link on a mathematical structure . Symbols are assigned to individual Boolean operators. This is used to clearly display a logic circuit - a combination of networked Boolean operators - and to derive the associated truth table .

Boolean operators are used, for example, in programming. The most common of these operators are the AND (conjunction), OR (disjunction), NOT (negation) and XOR (exclusive OR ) operator . Boolean operators are used, for example, in query languages , such as in the SQL expression

```  SELECT * FROM Customers
WHERE Country='Germany' AND City='Berlin';
```

with which all entries are selected from the Customers table that have Germany as the value for the Country column and Berlin as the value of the City column. Such a search procedure is also called a Boolean search procedure .

The NAND and NOR operators are also important operators in digital technology .