Oracle Database SQL — Question 128

Which three actions can you perform on an existing table containing data? (Choose three.)

Answer options

• A. Increase the width of a numeric column.
• B. Add a new column as the table's first column.
• C. Define a default value that is automatically inserted into a column containing nulls.
• D. Change a DATE column containing data to a NUMBER data type.
• E. Change the default value of a column.
• F. Add a new NOT NULL column with a DEFAULT value.

Correct answer: A, E, F

Explanation

Options A, E, and F are correct because they involve permissible alterations to a table's structure without violating data integrity. Increasing a column's width, changing a default value, and adding a NOT NULL column with a default value are all standard operations. In contrast, adding a new column as the first column (B) could disrupt existing data, and changing a DATE column to a NUMBER (D) would result in a data type conflict for existing entries.