# 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 \!= 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 |