# Boolean Functions

## Finding Strings Within Strings

These functions find a substring within a given string. They return true if the substring is found and false otherwise. In the table, field is the string to search. It is an expression evaluating to a `string` type. The string to search for is find.

Description Function Syntax
startsWith() `startsWith(string expr field, string find)` Determine whether a string starts with a substring
contains() `contains(string expr field, string find)` Determine whether a string contains a given substring
endsWith() `endsWith(string expr field, string find)` Determine whether a string ends with a given substring
like() `like(string expr field, string expr pattern, string esc)` Returns true if pattern is found within field

## Comparing Expressions with Constants

These functions find a constant (constN) in an expression (field). If one of the constants is found in field, true is returned. These functions return false otherwise.

Description Function Syntax
in `in(expr field, const1, const2, ...)` Return true if any of a list of items match the given expression
inList `inList(expr field, list)` Return true if an expression evaluates to one or more constants in list

## Find NULLs and NaNs

These functions check whether values can be used in further operations.

Description Function Syntax
isNull() `isNull(<type> expr field )` Returns true if field evaluates to NULL
isNan() `isNan(double value)` Returns true if value is NaN

## Compare Booleans

These functions operate on expressions evaluating to `boolean`. They are the logical functions Incorta supports.

Description Function Syntax
and() `and(bool expr1, bool expr2, . . .)` Determine whether a series of expressions evaluate to true
or() `or(bool expr1, bool expr2, . . .)` Determines whether any of a series of expressions evaluate to true
not() `not(bool expr)` Negates its expression argument

## Checking Ranges

Description Function Syntax
between() `between(double expr value, double expr min, double expr max)` Returns true if value is between min and max