Quiz for ALTER

Q1: Which SQL command is used to modify the structure of an existing table?

A. MODIFY B. CHANGE C. UPDATE D. ALTER

Q2: What does the ALTER statement do in SQL?

A. Modifies existing database objects B. Creates a new table C. Deletes a table D. None of the above

Q3: Which keyword is used with ALTER to add a new column?

A. ADD COLUMN B. MODIFY COLUMN C. NEW COLUMN D. INSERT COLUMN

Q4: What is the correct syntax to change the datatype of a column?

A. ALTER TABLE table_name MODIFY column_name new_datatype; B. ALTER TABLE table_name ADD column_name new_datatype; C. UPDATE table_name SET column_name = new_datatype; D. None of these

Q5: Which clause is used to remove a column?

A. DROP COLUMN B. DELETE COLUMN C. REMOVE COLUMN D. ERASE COLUMN

Q6: Can ALTER TABLE be used to rename a column?

A. Yes B. No C. Only in MySQL D. Only in SQL Server

Q7: Which of the following is used to rename a table?

A. ALTER TABLE old_name RENAME TO new_name; B. RENAME TABLE old_name TO new_name; C. CHANGE TABLE old_name new_name; D. MODIFY TABLE old_name new_name;

Q8: What happens if you use ALTER TABLE without specifying a change?

A. It causes an error B. The table is dropped C. A new table is created D. Nothing happens

Q9: Which DBMS allows changing column position using ALTER?

A. MySQL B. PostgreSQL C. SQLite D. Oracle

Q10: To rename a column, which keyword is used in MySQL?

A. CHANGE B. MODIFY C. RENAME COLUMN D. UPDATE

Q11: Which of the following is valid to add multiple columns?

A. ALTER TABLE table_name ADD (col1 INT, col2 VARCHAR(20)); B. ALTER TABLE table_name ADD col1 INT col2 VARCHAR(20); C. ADD col1, col2 TO table_name; D. ALTER table_name ADD col1, ADD col2;

Q12: Which clause changes a column’s name in PostgreSQL?

A. RENAME COLUMN B. CHANGE COLUMN C. MODIFY COLUMN D. REPLACE COLUMN

Q13: Can you modify a column constraint with ALTER?

A. Yes B. No C. Only in Oracle D. Only in SQL Server

Q14: What happens if you try to drop a column that is used in a constraint?

A. An error occurs B. Column is dropped anyway C. Constraint is automatically removed D. Table is dropped

Q15: Can ALTER be used to change a column’s default value?

A. Yes B. No C. Only during table creation D. Only with UPDATE

Q16: What is the result of using ALTER TABLE with ADD PRIMARY KEY?

A. Adds a new primary key B. Deletes existing key C. Drops table D. Creates new table

Q17: Can ALTER TABLE be used to add foreign keys?

A. Yes B. No C. Only during creation D. Only in views

Q18: Which ALTER syntax adds a NOT NULL constraint?

A. ALTER TABLE t MODIFY col datatype NOT NULL; B. ALTER TABLE t ADD col NOT NULL; C. ALTER col SET NOT NULL; D. MODIFY TABLE t SET col NOT NULL;

Q19: Which clause is used to drop a constraint?

A. DROP CONSTRAINT B. DELETE CONSTRAINT C. REMOVE CONSTRAINT D. ALTER CONSTRAINT

Q20: Which SQL engine does not support ALTER?

A. SQLite (limited) B. MySQL C. PostgreSQL D. SQL Server

Q21: Is it mandatory to commit after ALTER?

A. Depends on the DBMS B. Yes C. No D. Always auto-committed