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  • 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-------------------------------------------------------------------------->
    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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  • 原文地址:https://www.cnblogs.com/liufei88866/p/1105660.html
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