ALTER TABLE table_name ADD column_name datatype;            

ALTER TABLE table_name DROP  column_name;                            

ALTER TABLE table_name ALTER  column_name TYPE datatype;             

ALTER TABLE table_name RENAME TO new_name;                          

ALTER TABLE table_name RENAME column_name to new_column_name;         

ALTER TABLE table_name ALTER column_name {SET|DROP} NOT NULL;         

ALTER TABLE table_name ALTER column_name SET DEFAULT expression;