SQL ALTER TABLE
ALTER TABLE
The ALTER TABLE statement is used to add or drop columns in an existing
table.
ALTER TABLE table_name
ADD column_name datatype
ALTER TABLE table_name
DROP COLUMN column_name
|
Note: Some database systems don't allow the dropping of a column in a
database table (DROP COLUMN column_name).
Person:
| LastName |
FirstName |
Address |
| Pettersen |
Kari |
Storgt 20 |
Example
To add a column named "City" in the "Person" table:
ALTER TABLE Person ADD City varchar(30)
|
Result:
| LastName |
FirstName |
Address |
City |
| Pettersen |
Kari |
Storgt 20 |
|
Example
To drop the "Address" column in the "Person" table:
ALTER TABLE Person DROP COLUMN Address
|
Result:
| LastName |
FirstName |
City |
| Pettersen |
Kari |
|
| 
Printer friendly page
