1.参照完整性（外键关系）2.视图3.序列
同义词4.SQL DML DDL DCL5.create or replace view v1 as select aa.YHID,aa.YHXM,aa.YHNN,bb.ZZMM,bb.JTCY,cc.DWMC,bb.GL from A aa,B bb,C cc where aa.YHID=bb.YHID and aa.GZDW=cc.DWID6.select * from A group by id having count(distinct value)=17.select bb.* from A aa,B bb where aa.YHID=bb.YHID...
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