Using Scalar Subqueries in INSERT Requests
The following rules and restrictions apply to specifying scalar subqueries in INSERT
and INSERT … SELECT requests:
You can specify a scalar subquery as a parameterized value in the value list of a
simple INSERT request, but Teradata Database always interprets it as a noncorrelated
scalar subquery (see “Example: INSERT Using a Scalar Subquery” on page 388).
You cannot specify a noncorrelated scalar subquery as a value in a value list that
is assigned to an identity column in a simple INSERT request.
You can specify an INSERT request with scalar subqueries in the body of a trigger.
However, you cannot specify a simple INSERT request with a scalar subquery in its
value list in the body of a row trigger.
You can specify a scalar subquery in the SELECT component of an INSERT … SELECT request.
Teradata Database processes any noncorrelated scalar subquery specified in the SELECT
component of an INSERT … SELECT in a row trigger as a single‑column single‑row spool
instead of as a parameterized value.