SQL Command to Add Columns to a Table

The correct command to add columns to a table in SQL is 'alter'.

Here's why:

• alter is used to modify the structure of an existing table, including adding new columns.
• truncate removes all rows from a table but keeps the table structure intact.
• insert adds new rows to a table with existing columns.
• drop deletes an entire table and its data.

Example:

To add a column named 'email' to a table called 'users', you would use the following SQL statement:

ALTER TABLE users ADD email VARCHAR(255);

This command will add a new column named 'email' to the 'users' table. The column will be of type VARCHAR and have a maximum length of 255 characters.