> For the complete documentation index, see [llms.txt](https://vikram-bajaj.gitbook.io/cs-gy-6083-principles-of-database-systems/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://vikram-bajaj.gitbook.io/cs-gy-6083-principles-of-database-systems/sql/ddl-commands/alter-and-drop.md).

# Alter and Drop

The drop command will remove a table from the database schema.

```
drop table table_name
```

The alter command is used to add, delete, or modify columns in an existing table.

`alter table r add column column_name data_type`

`alter table r drop column column_name`

`alter table r alter column column_name data_type`

`alter table r modify [column] column_name data_type`