【多选题】
A <{p}>A column can be removed only if it contains no data.<{br/}><{/p}>
B <{p}>A column drop is implidtly committed<{br/}><{/p}>
C <{p}>A column that is referenced by another column in any other table cannot be dropped.<{br/}><{/p}>
D <{p}>A column must be set as unused before it is dropped from a table.<{br/}><{/p}>
E <{p}>A primary key column cannot be dropped.<{br/}><{/p}>
F <{p}>Multiple columns can be dropped simultaneously using the ALTER TABLE command.<{br/}><{/p}>
查看更多
