UNION

Combines the members of two or more result sets into a single set.

Syntax

set1 «UNION set2»

Parameters

set1

The name of a result set that resulted from the execution of a set-producing command.
Set1 and set2 must have the same component structure.

set2

The name of a result set that resulted from the execution of a set-producing command.
Set1 and set2 must have the same component structure.

Comments

When used within a FIND command, the set that results from the application of UNION contains all of the records from the specified sets, with duplicates being eliminated.

The sets must have the same component structure.

Example

find Employees (unrelated) WorkFor Managers keep Employees
find current (Employees -> Managers) -> MgrSet
% top level managers
find Employees WorkFor MgrSet keep Employees -> EmpSet
while
 find Employees WorkFor EmpSet (Employees -> Managers) -> EmpMgrSet
 if $setcount = 0
  break
 endif
 find EmpMgrSet keep Managers -> NewMgrSet
 find MgrSet union NewMgrSet -> MgrSet
endwhile

While the preceding program demonstrates the use of UNION, the program can be replaced with the single command shown below.

find Employees WorkFor Managers keep Managers -> MgrSet

 

Related Topics