-840 TOO MANY ITEMS RETURNED IN A SELECT, INSERT LIST, FROM MERGE, OR FROM UNNEST

Explanation
 The number of items returned in
the SELECT list, specified in an INSERT list, specified in a MERGE statement, or returned from an
invocation of UNNEST exceeds the allowable maximum of 750.

System action
 The statement cannot be processed.

Programmer response
 Determine whether all the information is
actually needed. For example, the number of items that are returned
by the SQL statement SELECT * FROM A, B, C is the sum of the number
of columns in all three tables. Not all column data might be needed.
Rewrite
the SQL statement so that only the necessary items of information
are returned, or break the SQL statement into two or more statements.

SQLSTATE
 54004