总结归纳：110个Oracle常用函数的总结(7)

文章作者 100test 发表时间 2007:07:02 12:16:04
来源 100Test.Com百考试题网

61.MAX(DISTINCT|ALL)
求最大值,ALL表示对所有的值求最大值,DISTINCT表示对不同的值求最大值,相同的只取一次
SQL> 0select max(distinct sal) from scott.emp.

MAX(DISTINCTSAL)
----------------
5000

62.MIN(DISTINCT|ALL)
求最小值,ALL表示对所有的值求最小值,DISTINCT表示对不同的值求最小值,相同的只取一次
SQL> 0select min(all sal) from gao.table3.

MIN(ALLSAL)
-----------
1111.11

63.STDDEV(distinct|all)
求标准差,ALL表示对所有的值求标准差,DISTINCT表示只对不同的值求标准差
SQL> 0select stddev(sal) from scott.emp.

STDDEV(SAL)
-----------
1182.5032

SQL> 0select stddev(distinct sal) from scott.emp.

STDDEV(DISTINCTSAL)
-------------------
1229.951

64.VARIANCE(DISTINCT|ALL)
求协方差

SQL> 0select variance(sal) from scott.emp.

VARIANCE(SAL)
-------------
1398313.9

65.GROUP BY
主要用来对一组数进行统计
SQL> 0select deptno,count(*),sum(sal) from scott.emp group by deptno.

DEPTNO COUNT(*) SUM(SAL)
--------- --------- ---------
10 3 8750
20 5 10875
30 6 9400

66.HAVING
对分组统计再加限制条件
SQL> 0select deptno,count(*),sum(sal) from scott.emp group by deptno having count(*)>=5.

DEPTNO COUNT(*) SUM(SAL)
--------- --------- ---------
20 5 10875
30 6 9400
SQL> 0select deptno,count(*),sum(sal) from scott.emp having count(*)>=5 group by deptno .

DEPTNO COUNT(*) SUM(SAL)
--------- --------- ---------
20 5 10875
30 6 9400

67.ORDER BY
用于对查询到的结果进行排序输出
SQL> 0select deptno,ename,sal from scott.emp order by deptno,sal desc.

DEPTNO ENAME SAL
--------- ---------- ---------
10 KING 5000
10 CLARK 2450
10 MILLER 1300
20 SCOTT 3000
20 FORD 3000
20 JONES 2975
20 ADAMS 1100
20 SMITH 800
30 BLAKE 2850
30 ALLEN 1600
30 TURNER 1500
30 WARD 1250
30 MARTIN 1250
30 JAMES 950
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