用PL/SQL画直方图

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-------------------------------------------------------------------------->


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PL/SQL procedure successfully completed.