ALTER TABLE

After creating a table, you often need to modify it — add a column, rename it, or change something. That is what ALTER TABLE is for.

Adding a Column

ALTER TABLE employees ADD COLUMN email TEXT;

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New columns are added at the end. Existing rows will have NULL for this column unless you specify a DEFAULT value.

Renaming a Table

ALTER TABLE employees RENAME TO staff;

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SQLite Limitations

I should be honest with you — SQLite has limited ALTER TABLE support compared to other databases. In SQLite, you can only:

Rename a table
Add a column

You cannot drop a column or change a column's type directly in SQLite. In MySQL or PostgreSQL, you have much more flexibility:

-- MySQL: Drop a column
-- ALTER TABLE employees DROP COLUMN email;

-- PostgreSQL: Change column type
-- ALTER TABLE employees ALTER COLUMN salary TYPE INTEGER;

If you ever switch databases, check the documentation. ALTER TABLE syntax varies a lot between systems.

🧪 Quick Quiz

Which SQL command is used to add a column to an existing table?

← CREATE TABLE

DROP TABLE →