A.同時(shí)修改字段數(shù)據(jù)類型和長(zhǎng)度B.修改計(jì)算列C.修改字段約束D.同時(shí)刪除字段和字段約束
A.學(xué)號(hào)varchar(10) B.成績(jī)int4 C.產(chǎn)量float D.價(jià)格decimal(8,4)
A.create database B.alter database C.drop database D.copy database