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至顶网软件频道菜鸟学oracle - 用PL/SQL画直方图

菜鸟学oracle - 用PL/SQL画直方图

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现在用的库里有一个MV是统计按小时的访问量的,数据如下代码: SQL> select * from mv_time_stat; TIME CNT ---------- ---------- 0

作者:中国IT实验室 来源:中国IT实验室 2007年10月1日

关键字: 直方图 plsql 数据库 ORACLE

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    现在用的库里有一个MV是统计按小时的访问量的,数据如下代码:

SQL> select * from mv_time_stat;



      TIME        CNT

---------- ----------

         0        187

         1         51

         2         34

         3         19

         4         19

         5         20

         6         50

         7        107

         8        682

         9       1342

        10       1854

        11       1292

        12       1416

        13       1180

        14       1217

        15       1573

        16       1785

        17       1469

        18       1892

        19       1907

        20       1602

        21       1540

        22       1013

        23        441



24 rows selected.




   某年月日,突发奇想,打算在sqlplus下面按上面的数据画个直方图出来,首先写了个竖列的(因为好写):

代码:

SQL> COL Time FORMAT A7
SQL> SELECT LPAD(DECODE(TIME,TO_CHAR(SYSDATE,'HH24'),'NOW: '||
TO_CHAR(TIME),TO_CHAR(TIME)),7,' ') AS "Time",
  2  SUBSTR('|'||LPAD('> '||CNT,CEIL(CNT/A.TOTAL*300)+
LENGTH(TO_CHAR(CNT))+1,'-'),1,35) AS "    Count per hour"
  3  FROM MV_TIME_STAT,(SELECT SUM(CNT) AS TOTAL FROM MV_TIME_STAT) A;
COL Time CLEAR

Time        Count per hour
------- -----------------------------------------------------------------
      0 |--> 187
      1 |> 51
      2 |> 34
      3 |> 19
      4 |> 19
      5 |> 20
      6 |> 50
      7 |-> 107
NOW: 8 |---------> 682
      9 |-----------------> 1342
     10 |------------------------> 1854
     11 |-----------------> 1292
     12 |------------------> 1416
     13 |---------------> 1180
     14 |----------------> 1217
     15 |--------------------> 1573
     16 |-----------------------> 1785
     17 |-------------------> 1469
     18 |-------------------------> 1892
     19 |-------------------------> 1907
     20 |---------------------> 1602
     21 |--------------------> 1540
     22 |-------------> 1013
     23 |-----> 441

24 rows selected.



    然后又想,怎么样把它横过来,到网上查资料,又突击学习了下分析函数,写了一个过程是这个样子的:

代码:

CREATE OR REPLACE PROCEDURE HISTOGRAPH(HEIGHT NUMBER DEFAULT 15) AS
  MAX_ONE NUMBER;
  STR_LINE VARCHAR(120);
  STR_TEMP VARCHAR(120);
  I NUMBER;
BEGIN
  DBMS_OUTPUT.PUT_LINE(LPAD('^',14,' '));
  SELECT MAX(CNT) INTO MAX_ONE FROM MV_TIME_STAT;
  FOR I IN 1 .. HEIGHT+1 LOOP
    STR_LINE:=LPAD(TO_CHAR(MAX_ONE-(I-1)*MAX_ONE/HEIGHT,'99999')||'-'||
TO_CHAR(MAX_ONE-(I-2)*MAX_ONE/HEIGHT,'99999')||'|',14,'0');
    SELECT MAX(SYS_CONNECT_BY_PATH(
      DECODE(SIGN(CNT-MAX_ONE+(I-1)*MAX_ONE/HEIGHT),-1,
        DECODE(SIGN(CNT-MAX_ONE+(I-2)*MAX_ONE/HEIGHT),-1,'^','*'),
      '|'),
    '  '))  INTO STR_TEMP
    FROM MV_TIME_STAT
    START WITH TIME=0
    CONNECT BY PRIOR TIME=TIME-1;
    STR_LINE:=STR_LINE||STR_TEMP;
    DBMS_OUTPUT.PUT_LINE(REPLACE (STR_LINE,'^',' '));
  END LOOP;
  SELECT MAX(SYS_CONNECT_BY_PATH(TO_CHAR(TIME,'00'),'^'))  INTO STR_TEMP
  FROM MV_TIME_STAT
  START WITH TIME=0
  CONNECT BY PRIOR TIME=TIME-1;
  DBMS_OUTPUT.PUT_LINE(LPAD('0',14,' ')||LPAD('>',LENGTH(REPLACE(STR_TEMP,' '))+3,'-'));
  DBMS_OUTPUT.PUT_LINE(REPLACE(LPAD('^',14,' ')||REPLACE(STR_TEMP,' '),'^',' '));
END;
/    

Procedure created.

SQL> exec histograph;
             ^
  1907-  2034|                                                           |
  1780-  1907|                                |                 |     |  |
  1653-  1780|                                |                 |     |  |
  1526-  1653|                                |              |  |     |  |  |  |
  1398-  1526|                                |     |        |  |  |  |  |  |  |
  1271-  1398|                             |  |  |  |        |  |  |  |  |  |  |
  1144-  1271|                             |  |  |  |  |  |  |  |  |  |  |  |  |
  1017-  1144|                             |  |  |  |  |  |  |  |  |  |  |  |  |
   890-  1017|                             |  |  |  |  |  |  |  |  |  |  |  |  |  |
   763-   890|                             |  |  |  |  |  |  |  |  |  |  |  |  |  |
   636-   763|                          |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
   509-   636|                          |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
   381-   509|                          |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
   254-   381|                          |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
   127-   254|  |                       |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
     0-   127|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
             0-------------------------------------------------------------------------->
               00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23

PL/SQL procedure successfully completed.


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