SQL - Alter Table
Overview
ALTER TABLE modifies existing tables. Engines differ in supported operations. SQLite supports adding columns and renaming tables/columns (modern versions), but not dropping columns in older versions.
ALTER TABLE employees ADD COLUMN middle_name VARCHAR(50);
ALTER TABLE employees DROP COLUMN middle_name;
ALTER TABLE employees RENAME COLUMN first_name TO given_name;
ALTER TABLE employees ADD middle_name NVARCHAR(50);
ALTER TABLE employees DROP COLUMN middle_name;
EXEC sp_rename 'employees.first_name', 'given_name', 'COLUMN';
ALTER TABLE employees ADD COLUMN middle_name TEXT;
-- Renames supported (3.25+):
ALTER TABLE employees RENAME COLUMN first_name TO given_name;
-- Dropping columns historically unsupported (use create-copy pattern)
Live Demo (SQLite)
| cid | name | type | notnull | dflt_value | pk |
|---|---|---|---|---|---|
| 0 | id | INTEGER | 0 | 1 | |
| 1 | name | TEXT | 0 | 0 | |
| 2 | TEXT | 0 | 0 |