alter

删除primary key

alter table tablename drop constraint tablename_pkey;

添加primary key

alter table tablename add primary key(colname);

添加/删除非空约束

alter table tablename alter COLUMN colname set/drop not null;

添加列

alter table tablename ADD colname datatype;

删除列

alter table tablename drop colname

更改列数据类型

alter table tablename alter colname TYPE datatype;

更改表名

alter table tablename RENAME TO newtablename