DRDS 支持如下比较运算符：
| 函数名 | 描述 |
| BETWEEN … AND … | Check whether a value is within a range of values |
| = | Equal operator |
| <=> | NULL-safe equal to operator |
| > | Greater than operator |
| >= | Greater than or equal operator |
| IS | Test a value against a boolean |
| IS NOT | Test a value against a boolean |
| IS NOT NULL | NOT NULL value test |
| IS NULL | NULL value test |
| < | Less than operator |
| <= | Less than or equal operator |
| LIKE | Simple pattern matching |
| NOT BETWEEN … AND … | Check whether a value is not within a range of values |
| !=, <> | Not equal operator |
| NOT LIKE | Negation of simple pattern matching |