How do I Alter Table Column datatype on more than 1 column?

Question

For example:

ALTER TABLE webstore.Store MODIFY COLUMN (
  ShortName VARCHAR(100),
  UrlShort VARCHAR(100)
);

The above however does not work. I am using MySql 5.x

Answer 1

ALTER TABLE can do multiple table alterations in one statement, but MODIFY COLUMN can only work on one column at a time, so you need to specify MODIFY COLUMN for each column you want to change:

ALTER TABLE webstore.Store
  MODIFY COLUMN ShortName VARCHAR(100),
  MODIFY COLUMN UrlShort VARCHAR(100);

Also, note this warning from the manual:

When you use CHANGE or MODIFY, column_definition must include the data type and all attributes that should apply to the new column, other than index attributes such as PRIMARY KEY or UNIQUE. Attributes present in the original definition but not specified for the new definition are not carried forward.