-533 INVALID MULTIPLE-ROW INSERT

Explanation
An INSERT operation with a subselect attempted to insert multiple rows
into a self-referencing table.

The subselect of the INSERT operation should return no more than one row
of data.

System action
The INSERT statement cannot be executed.  The contents of the object table
are unchanged.

Programmer response
Examine the search condition of the subselect to make sure that no more
than one row of data is selected.

SQLSTATE
21501 