company logo

Having specification

Keywords:  filter

The HAVING clause describes a filter as post-condition for filtering data in the SELECT data source or calling object collection. The filter condition is an expression returning true or false, which must be defined in terms of the SELECT operation (or calling object) data type. When a HAVING filter condition has been defined, instances in the calling object collection returning false will be ignored.

In an operation path, the HAVING operation always applies on the preceding collection, i.e. in this case, the distinction between WHERE and HAVING becomes obsolete.

The HAVING operation will not alter the data type of the instances, i.e. the output instances for the operation have the same data type as the input. This is also valid for the collection attributes (e.g. weak-typed or sort order).

Definition: 

having_spec := _having '(' operand ')'

Related topics