drop table if exists t1; create table t1(objid BIGINT not null, tablename varchar(64), oid BIGINT not null, test BIGINT, PRIMARY KEY (objid), UNIQUE(tablename)) engine=BDB; insert into t1 values(1, 't1',4,9); insert into t1 values(2, 'metatable',1,9); insert into t1 values(3, 'metaindex',1,9 ); select * from t1; objid tablename oid test 1 t1 4 9 2 metatable 1 9 3 metaindex 1 9 alter table t1 drop column test;