Altering a Table

The ALTER TABLE command is used to alter a table. Columns can be added or removed after a table is created.

Adding a Column

Syntax

ALTER TABLE <table-name> ADD <column-name> <column-constraints>;

Example

ALTER TABLE Companies 
ADD stock_symbol VARCHAR(5) UNIQUE, 
ADD stock_price REAL;

Removing a Column

Syntax

ALTER TABLE <table-name> DROP <column-name>;

Example

ALTER TABLE Companies
DROP stock_symbol, 
DROP stock_price;