Choose the best answer. Examine this configuration: 1. CDB1 is a container database. 2.DEFAULT_SHARING is METADATA. 3. APP_ROOT is an application root contained in CDB1. 4. APP_PDB1 is an…

Question

Options

• ASAL will be added to APP_PDB1.EMP, with 0 in columns of existing rows.
• BSAL will be added to APP_PDB1.EMP, with NULLs in columns of existing rows.
• CIt will return an error because the SYNC operation is not allowed when constraints are added
• DIt will return an error because EMP is not empty in APP_ROOT.
• EIt will return an error because EMP.SAL is empty in APP_ROOT.

• A
  8% (5)
• B
  3% (2)
• C
  3% (2)
• D
  69% (43)
• E
  16% (10)

Explanation

Option D is correct because ALTER TABLE emp ADD (sal NUMBER NOT NULL) - recorded during the upgrade in APP_ROOT - is replayed against APP_PDB1 when SYNC executes. Oracle cannot add a NOT NULL column without a DEFAULT clause to a table that already contains rows; existing rows would have no valid value for SAL, violating the constraint, so the SYNC operation raises an error.

Why the distractors fail:

• A & B are impossible: Oracle never silently fabricates zeros or permits NULLs for a NOT NULL column - both scenarios directly violate the constraint definition.
• C is wrong: SYNC does not generically prohibit DDL that adds constraints; the failure is data-driven, not constraint-type-driven.
• E is wrong: the column SAL doesn't yet exist in APP_PDB1 before SYNC, so "SAL is empty in APP_ROOT" is meaningless - the blocking issue is the existing row data, not a missing column value.

Memory tip: When writing upgrade scripts for Application Containers, treat NOT NULL ADD like a loaded gun - it only fires safely on an empty table. Always pair NOT NULL with a DEFAULT value when existing rows may be present: ADD (sal NUMBER DEFAULT 0 NOT NULL).

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