ALTER TABLE
command
Modifies an existing table structure: add/drop columns, change data types, add indexes.
Syntax
ALTER TABLE table ADD | DROP | MODIFY | RENAME ...;
Example
sql
-- Add column
ALTER TABLE users ADD COLUMN phone VARCHAR(20) AFTER email;
-- Drop column
ALTER TABLE users DROP COLUMN phone;
-- Modify column type
ALTER TABLE products MODIFY COLUMN price DECIMAL(10,2) NOT NULL;
-- Add index
ALTER TABLE users ADD INDEX idx_email (email);
-- Rename table
ALTER TABLE old_name RENAME TO new_name;