Page History

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CREATE TABLE Person (id INT, name VARCHAR(32), lastname VARCHAR(32), taxid int);

ALTER TABLE Person ADD COLUM
NCOLUMN residence VARCHAR(2) DEFAULT "GB";

ALTER TABLE Person DROP COLUMN lastname, taxid;

ALTER TABLE Person ADD COLUMN lastname DEFAULT "N/A";

This sequence of modifications will result in the following schema history

With this history, upgrading a tuple (1, "John", "Doe") of version 1 to version 4 means erasing columns lastname and taxid and adding columns residence with default "GB" and lastname (the column is returned back) with default "N/A" resulting in tuple (1, "John", "GB", "N/A").

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