Before any changes to database structure are attempted one should first:
A. clearly understand the current structure and contents of the database only.
B. test any changes on a test database only.
C. create a complete backup of the operational database only.
D. All of the above should be done.
Answer: Option D
A. Correlated subqueries only
B. EXISTS/NOT EXISTS expressions only
C. Both of the above are helpful
D. None of the above are helpful
A. MODIFY TABLE TableName DROP COLUMN ColumnName
B. MODIFY TABLE TableName DROP ColumnName
C. ALTER TABLE TableName DROP COLUMN ColumnName
D. ALTER TABLE TableName DROP ColumnName
A. database is structured.
B. database is well-designed.
C. database has no data.
D. database is relatively small.
A. RENAME TABLE
B. CHANGE TABLE
C. ALTER TABLE
D. None of the above is correct