Comparisons

Comparison Operators

The table below shows the standard comparison operators. Whenever either of the input arguments is NULL, the output of the comparison is NULL.

Operator Description Example Result
< less than 2 < 3 TRUE
> greater than 2 > 3 FALSE
<= less than or equal to 2 <= 3 TRUE
>= greater than or equal to 4 >= NULL NULL
= equal NULL = NULL NULL
<> or != not equal 2 <> 2 FALSE

Comparison Predicates

Besides the comparison operators there are also a set of comparison operators. These behave much like operators, but have special syntax mandated by the SQL standard. They are shown in the table below.

Predicate Description
a BETWEEN x AND y equivalent to a >= x AND a <= y
a NOT BETWEEN x AND y equivalent to a < x OR a > y
expression IS NULL TRUE if expression is NULL, FALSE otherwise
expression ISNULL alias for IS NULL (non-standard)
expression IS NOT NULL FALSE if expression is NULL, TRUE otherwise
expression NOTNULL alias for IS NOT NULL (non-standard)