How do I add a column to an existing SQL table?

How do I add a column to an existing SQL table?

You can use the ALTER TABLE statement. For example: ALTER TABLE table_name ADD column_name column_type;

Can I add multiple columns at once?

Yes, you can add multiple columns by separating them with commas. For example: ALTER TABLE table_name ADD column1_name column1_type, ADD column2_name column2_type;

What if I want to set a default value for the new column?

You can set a default value by using the DEFAULT keyword. For example: ALTER TABLE table_name ADD column_name column_type DEFAULT default_value;

Are there any restrictions on the column types I can add?

Yes, the column types must be compatible with the existing data in the table, and some databases have specific restrictions.