bool

The bool data type can have one of two states: true or false, as well as the null value.

Alias: boolean.

bool Definition

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A value is considered true in any of the following cases:

• If it’s the actual bool value true.
• If it’s one of the following case-insensitive strings: 'true', 't', 'yes', 'y'.
• If it’s a numeric value equal to 1 (including 1.0).

A value is considered false in any of the following cases:

• If it’s the actual bool value false.
• If it’s one of the following case-insensitive strings: 'false', 'f', 'no', 'n'.
• If it’s a numeric value equal to 0 (including 0.0).

Any values that couldn’t be converted to bool are considered null.

Comparing bool to Numbers

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When comparing bool values to numbers, only 1 is considered true. For example:

However, when converting a value to a bool, all non-zero numbers are converted to true:

bool as a Filter

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To search for any values that are considered true, filter on the literal true value:

• dataset="foo" something=true
• dataset="foo" | where something==true

These will match on:

• Booleans with value true.
• The following case-insensitive strings: 'true', 't', 'yes', 'y'.
• Numeric values equal to 1.

To search for any values that are considered false, filter on the literal false value:

• dataset="foo" something=false
• dataset="foo" | where something==false

These will match on:

• Booleans with value false.
• The following case-insensitive strings: 'false', 'f', 'no', 'n'.
• Numeric values equal to 0.

Note that searching on "true" or "false” literals with quotes does a string match instead. This means that:

dataset="foo" | where something=="true"

Will match on "true" and true, but not on 1, "yes" or any other bool values.

bool as Function Input

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For any functions that take bool arguments, the values will be automatically converted to true, false or null, according to our bool definition. Mind that all non-zero numbers are converted to true.

For conditional functions, null is treated as false.

bool and the Logical NOT Operator

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Both the logical NOT ! operator and the not function:

• Return false for all values considered true by the bool definition. Mind that all non-zero numbers are converted to true.
• Return true for all values considered false by the bool definition.
• Return null if passed null, or for any values that can’t be converted to true or false.