ALTER TABLE operations in MySQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the ALTER TABLE statement do in SQL?

It changes the structure of an existing table, such as adding, deleting, or modifying columns.

beginner

How do you add a new column named age of type INT to a table called users?

Use: ALTER TABLE users ADD COLUMN age INT;

intermediate

How can you rename a column fullname to full_name in MySQL?

Use: ALTER TABLE table_name CHANGE fullname full_name datatype; where you specify the datatype again.

beginner

What is the command to drop (delete) a column named address from a table customers?

Use: ALTER TABLE customers DROP COLUMN address;

intermediate

How do you change the data type of a column price to DECIMAL(10,2) in MySQL?

Use: ALTER TABLE table_name MODIFY COLUMN price DECIMAL(10,2);

Which SQL command adds a new column to an existing table?

A DROP TABLE COLUMN

B ALTER TABLE ADD COLUMN

C INSERT INTO TABLE

D CREATE TABLE ADD COLUMN

The correct syntax to add a column is using ALTER TABLE with ADD COLUMN.

How do you remove a column named 'email' from a table 'contacts'?

A ALTER TABLE contacts DROP COLUMN email;

B DELETE COLUMN email FROM contacts;

C ALTER TABLE contacts REMOVE email;

D DROP TABLE contacts.email;

The correct syntax to remove a column is ALTER TABLE with DROP COLUMN.

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

A CHANGE

B RENAME COLUMN

C MODIFY

D ALTER COLUMN

MySQL uses CHANGE to rename a column and requires the datatype to be specified.

Which command changes the data type of a column?

A ALTER TABLE DROP

B ALTER TABLE RENAME

C ALTER TABLE ADD

D ALTER TABLE MODIFY

MODIFY is used to change the data type or definition of a column.

What happens if you run ALTER TABLE table_name ADD COLUMN new_col VARCHAR(50);?

A Renames the table to new_col

B Deletes the column new_col

C Adds a new column named new_col with type VARCHAR(50)

D Changes the data type of new_col

This command adds a new column named new_col with the specified type.

Explain how to add, rename, and delete columns in a MySQL table using ALTER TABLE.

Think about the keywords ADD, CHANGE, and DROP with ALTER TABLE.

Describe the difference between MODIFY and CHANGE in ALTER TABLE operations.

One is for renaming, the other for changing type.