ALTER TABLE modifies an existing table structure. Add columns, change data types, or add constraints.

Add New Column

ALTER TABLE customers ADD phone VARCHAR(20);

Drop Column

ALTER TABLE customers DROP COLUMN phone;

Modify Column Type

ALTER TABLE products MODIFY price DECIMAL(12,2);

Rename Column

ALTER TABLE customers RENAME COLUMN name TO full_name;

Add Primary Key

ALTER TABLE orders ADD PRIMARY KEY (id);

Add Foreign Key

ALTER TABLE orders

ADD FOREIGN KEY (customer_id) REFERENCES customers(id);

Add Index

ALTER TABLE customers ADD INDEX idx_email (email);

Generate ALTER Statements

AI2sql helps you modify tables safely with proper syntax.