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SQL Alter Table

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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  


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