# Comparison operators
<a name="sql-supported-comparision"></a>

AWS IoT SiteWise supports the following comparison operators. All comparison operations are available for built in data types and evaluate to a boolean.


**Logical operators**  

|  **Operator**  |  **Description**  | 
| --- | --- | 
|  `<`  |  Less than  | 
|  `>`  |  Greater than  | 
|  `<=`  |  Less than or equal to  | 
|  `>=`  |  Greater than or equal to  | 
|  `=`  |  Equals  | 
|  `!=`  |  Not equal  | 


**Comparison operation truth table for non numeric values**  

|  **Type**  |  **Type >= x**  |  **Type <= x**  |  **Type > x**  |  **Type < x**  |  **Type = x**  |  **Type \$1= x**  | 
| --- | --- | --- | --- | --- | --- | --- | 
|  `NULL`  |  `FALSE`  |  `FALSE`  |  `FALSE`  |  `FALSE`  |  `FALSE`  |  `TRUE`  | 

Some predicates behave like operators but have special syntax. See below:


**Comparision predicates**  

|  **Operator**  |  **Description**  | 
| --- | --- | 
|  `IS NULL`  |  Tests if a value is `NULL`.  | 
|  `IS NOT NULL`  |  Tests if a value is not `NULL`.  | 

## NaN operators
<a name="sql-supported-comparision-nan"></a>

 `NaN`, or 'Not a Number', is a special value in floating-point arithmetic. Here is a list of `NaN` comparisions and how they work. 
+ `NaN` values must be enclosed within single quotes. For example, '`NaN`'.
+ `NaN` values are considered equal to each other.
+ `NaN` is greater than other numeric values.
+ In aggregate functions like `AVG()`, `STDDEV()`, and `SUM()`, if any values are `NaN`, the result is `NaN`. 
+ In aggregate functions like `MAX()` and `MIN()`, `NaN` values are included in the calculations.


**NaN value comparisions**  

|  **Comparison**  |  **Result**  | 
| --- | --- | 
|  `'NaN' ≥ x`  |  True  | 
|  `'NaN' ≤ x`  |  True if x equals NaN, False otherwise  | 
|  `'NaN' > x`  |  False if x equals NaN, True otherwise  | 
|  `'NaN' < x`  |  False  | 
|  `'NaN' = x`  |  True if x equals NaN, False otherwise  | 
|  `'NaN' != x`  |  False if x equals NaN, True otherwise  |