7. Which of the following commands drops any columns marked as unused from the SECUSTOMERORDERS table? a. DROP COLUMN FROM secustomerorders WHERE column_status = UNUSED; b. ALTER TABLE secustomerorder…
7. Which of the following commands drops any columns marked as unused from the
SECUSTOMERORDERS table?
a. DROP COLUMN FROM secustomerorders WHERE column_status = UNUSED;
b. ALTER TABLE secustomerorders DROP UNUSED COLUMNS;
c. ALTER TABLE secustomerorders DROP (unused);
d. DROP UNUSED COLUMNS;
8. Which of the following statements is correct?
a. A table can contain a maximum of only one column marked as unused.
b. You can delete a table by removing all columns in the table.
c. Using the SET UNUSED clause allows you to free up storage space used by a column.
d. None of the above statements are correct.
9. Which of the following commands removes all data from a table but leaves the table’s
structure intact?
a. ALTER TABLE secustomerorders DROP UNUSED COLUMNS;
b. TRUNCATE TABLE secustomerorders;
c. DELETE TABLE secustomerorders;
d. DROP TABLE secustomerorders;
10. Which of the following commands changes a table’s name from OLDNAME to NEWNAME?
a. RENAME oldname TO newname;
b. RENAME table FROM oldname TO newname;
c. ALTER TABLE oldname MODIFY TO newname;
d. CREATE TABLE newname (SELECT * FROM oldname);
11. The default width of a VARCHAR2 field is:
a. 1
b. 30
c. 255
d. None—there’s no default width for a VARCHAR2 field.
12. Which of the following is not a valid statement?
a. You can change the name of a table only if it doesn’t contain any data.
b. You can change the length of a column that doesn’t contain any data.
c. You can delete a column that doesn’t contain any data.
d. You ca
OR