SQL alter table column commands

Today I had to change a little bit some column of some database tables. I don't like in future to search the SQL-Commands again, so I like to add them to
my blog and hope, that they will also helpfully for you.
Drop Not Null Constraint from column :

ALTER TABLE TEST_ABC MODIFY ID_CUSTOMER bigint(20) NULL

Remove column

ALTER TABLE SALESORDER DROP columname1

Add column

ALTER TABLE CUSTOMER_ADRESS ADD testcolumnName2 VARCHAR(255) NULL

Rename column

ALTER TABLE WEB_SITE change `headerURL`  `headerURLorData` text

All commands are tested on MySQL 5.5.28.