Logical (binary) operators

  • Article

The following logical operators can be used to perform comparisons and evaluations:

Operator name Syntax Meaning
Equality == Returns true if both operands are non-null and equal to each other. Otherwise, returns false.
Inequality != Returns true if any of the operands are null or if the operands aren't equal to each other. Otherwise, returns false.
Logical and and Returns true only if both operands are true.
Logical or or Returns true if either of the operands is true, regardless of the other operand.

Note

These logical operators are sometimes referred-to as Boolean operators, and sometimes as binary operators. The terms are interchangeable.

How logical operators work with null values

Null values adhere to the following rules:

Operation Result
bool(null) == bool(null) false
bool(null) != bool(null) false
bool(null) and true false
bool(null) or true true

Examples

Equality

The following query returns a count of all storm events where the event type is "Tornado".

Run the query

StormEvents
| where EventType == "Tornado"
| count

Output

Count
1238

Inequality

The following query returns a count of all storm events where the event type isn't "Tornado".

Run the query

StormEvents
| where EventType != "Tornado"
| count

Output

Count
57828

Logical and

The following query returns a count of all storm events where the event type is "Tornado" and the state is "KANSAS".

Run the query

StormEvents
| where EventType == "Tornado" and State == "KANSAS"
| count

Output

Count
161

Logical or

The following query returns a count of all storm events where the event type is "Tornado" or "Thunderstorm Wind".

Run the query

StormEvents
| where EventType == "Tornado" or EventType != "Thunderstorm Wind"
| count

Output

Count
14253

Null values

The following query shows that null values are treated as false.

Run the query

print iff(bool(null) and true, true, false)

Output

print_0
false