Using ALTER TABLE

Go Up to Altering Tables

ALTER TABLE allows you to make the following changes to an existing table:

• Add new column definitions. To create a column using an existing name, you must drop existing column definitions before adding new ones.
• Add new table constraints. To create a constraint using an existing name, you must drop existing constraints with that name before adding a new one.
• Drop existing column definitions without adding new ones.
• Drop existing table constraints without adding new ones.
• Modify column names, data types, and position

For a detailed specification of ALTER TABLE syntax, see the Language Reference.

Topics

• Adding a New Column to a Table
• Adding New Table Constraints
• Dropping an Existing Column from a Table
• Dropping Existing Constraints from a Column
• Modifying Columns in a Table
• Summary of ALTER TABLE Arguments