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对于表中两行记录完全一样的情况，可以用下面语句获取到去掉重复数据后的记录：select distinct * from 表名可以将查询的记录放到临时表中，然后再将原来的表记录删除，最后将临时表的数据导回原来的表中。如下：CREATE TABLE 临时表 AS (select distinct * from 表名);truncate table 正式表; --注：原先由于笔误写成了d

1. ORACLE SELECT * FROM TABLENAME WHERE ROWNUMHQL: from tablename t order by t.createTime desc where rownum2. INFORMIX     SELECT FIRST N * FROM TABLENAME 3. DB2 SELECT * ROW_NUMBE

1. 哪些部门的人数比20 号部门的人数多。SELECT DEPTNO,COUNT(*) FROM EMP     GROUP BY DEPTNO      HAVING COUNT(*) >            (SELECT COUNT(*) FROM EMP              WHERE DEPTNO = 20            );        

Oracle 删除重复数据的几种方法去重第一种：distinctcreate table tmp_t3 as select distinct * from t3;drop table t3;alter table tmp_t2 rename to t3;-- 第二种，用rowiddelete from t2 where rowid <>( select min(r...