oracle行转换列解决办法

转Oracle 行列转换1、固定列数的行列转换如student subject grade--------- ---------- --------student1 语文 80student1 数学 70student1 英语 60student2 语文 90student2 数学 80student2 英语 100……转换为语文 数学 英语student1 80 70 60student2 90 80 100……语句如下：select student, sum(decode(subject,'语文', grade,null)) "语文",sum(decode(subject,'数学', grade,null)) "数学",sum(decode(subject,'英语', grade,null)) "英语"from tablegroup by student;　2、不定列行列转换如c1 c2--- -----------1 我1 是1 谁2 知2 道3 不……转换为1 我是谁2 知道3 不这一类型的转换可以借助于PL/SQL来完成，这里给一个例子CREATE OR REPLACE FUNCTION get_c2(tmp_c1 NUMBER)RETURN VARCHAR2ISCol_c2 VARCHAR2(4000);BEGINFOR cur IN (SELECT c2 FROM t WHERE c1=tmp_c1) LOOPCol_c2 := Col_c2||cur.c2;END LOOP;Col_c2 := rtrim(Col_c2,1);RETURN Col_c2;END;select distinct c1 ,get_c2(c1) cc2 from table;或者不用pl/sql，利用分析函数和 CONNECT_BY 实现：SELECT c1, SUBSTR (MAX (SYS_CONNECT_BY_PATH (c2, ';')), 2) NAME    FROM (SELECT c1, c2, rn, LEAD (rn) OVER (PARTITION BY c1 ORDER BY rn) rn1            FROM (SELECT c1, c2, ROW_NUMBER () OVER (ORDER BY c2) rn                    FROM t))START WITH rn1 IS NULLCONNECT BY rn1 = PRIOR rnGROUP BY c1;3、列数不固定（交叉表行列转置）这种是比较麻烦的一种，需要借助pl/sql：原始数据：CLASS1     CALLDATE         CALLCOUNT1          2005-08-08       401          2005-08-07       62          2005-08-08       773          2005-08-09       333          2005-08-08       93          2005-08-07       21转置后：CALLDATE     CallCount1 CallCount2 CallCount3------------ ---------- ---------- ----------2005-08-09   0          0          332005-08-08   40         77         92005-08-07 　6 　　　　　0          21试验如下：1）. 建立测试表和数据CREATE TABLE t(    class1 VARCHAR2(2 BYTE),    calldate DATE,    callcount INTEGER);INSERT INTO t(class1, calldate, callcount)VALUES ('1', TO_DATE ('08/08/2005', 'MM/DD/YYYY'), 40);INSERT INTO t(class1, calldate, callcount)VALUES ('1', TO_DATE ('08/07/2005', 'MM/DD/YYYY'), 6);INSERT INTO t(class1, calldate, callcount)VALUES ('2', TO_DATE ('08/08/2005', 'MM/DD/YYYY'), 77);INSERT INTO t(class1, calldate, callcount)VALUES ('3', TO_DATE ('08/09/2005', 'MM/DD/YYYY'), 33);INSERT INTO t(class1, calldate, callcount)VALUES ('3', TO_DATE ('08/08/2005', 'MM/DD/YYYY'), 9);INSERT INTO t(class1, calldate, callcount)VALUES ('3', TO_DATE ('08/07/2005', 'MM/DD/YYYY'), 21); COMMIT ; 2）. 建立ref cursor准备输出结果集 CREATE OR REPLACE PACKAGE pkg_getrecordIS    TYPE myrctype IS REF CURSOR;END pkg_getrecord;/3）. 建立动态sql交叉表函数，输出结果集 CREATE OR REPLACE FUNCTION fn_rs    RETURN pkg_getrecord.myrctypeIS    s VARCHAR2 (4000);     CURSOR c1 IS    SELECT ',sum(case when Class1='            || class1            || ' then CallCount else 0 end)'            || ' "CallCount'            || class1            || '"' c2    FROM t    GROUP BY class1;    r1 c1%ROWTYPE;    list_cursor pkg_getrecord.myrctype;BEGIN    s := 'select CallDate ';    OPEN c1;    LOOP        FETCH c1 INTO r1;        EXIT WHEN c1%NOTFOUND;        s := s || r1.c2;    END LOOP;    CLOSE c1;    s := s || ' from T group by CallDate order by CallDate desc ';    OPEN list_cursor FOR s;    RETURN list_cursor;END fn_rs;/ 4）. 测试在sql plus下执行：var results refcursor;exec :results := fn_rs;print results;CALLDATE        CallCount1 CallCount2 CallCount3--------------- ---------- ---------- ----------2005-08-09      0          0          332005-08-08      40         77         92005-08-07      6          0          21典型实例讲解：假如有如下表，其中各个i值对应的行数是不定的SQL> select * from t;I A D———- ———- ——————-1 b 2008-03-27 10:55:421 a2008-03-27 10:55:461 d 2008-03-27 10:55:302 z 2008-03-27 10:55:552 t 2008-03-27 10:55:59要获得如下结果，注意字符串需要按照D列的时间排序：1 d,b,a2 z,t这是一个比较典型的行列转换，有好几种实现方法 1.自定义函数实现create or replace function my_concat(n number)return varchar2istype typ_cursor is ref cursor;v_cursor typ_cursor;v_temp varchar2(10);v_result varchar2(4000):= ”;v_sql varchar2(200);beginv_sql := ‘select a from t where i=’ || n ||’ order by d’;open v_cursor for v_sql;loopfetch v_cursor into v_temp;exit when v_cursor%notfound;v_result := v_result ||’,’ || v_temp;end loop;return substr(v_result,2);end;SQL> select i,my_concat(i) from t group by i;I MY_CONCAT(I)———- ——————–1 d,b,a2 z,t虽然这种方式可以实现需求，但是如果表t的数据量很大，i的值又很多的情况下，因为针对每个i值都要执行一句select，扫描和排序的次数和i的值成正比，性能会非常差。2.使用sys_connect_by_pathselect i,ltrim(max(sys_connect_by_path(a,’,')),’,') afrom(select i,a,d,min(d) over(partition by i) d_min,(row_number() over(order by i,d))+(dense_rank() over (order by i)) numidfrom t)start with d=d_min connect by numid-1=prior numidgroup by i;从执行计划上来看，这种方式只需要扫描两次表，比自定义函数的方法，效率要高很多，尤其是表中数据量较大的时候。3.使用wm_sys.wm_concat这个函数也可以实现类似的行列转换需求，但是似乎没有办法做到直接根据另外一列排序，所以需要先通过子查询或者临时表排好序SQL> select i,wmsys.wm_concat(a) from t group by i;I WMSYS.WM_CONCAT(A)———- ——————–1 b,a,d2 z,tSQL> select i,wmsys.wm_concat(a)2 from3 (select * from t order by i,d)4 group by i;I WMSYS.WM_CONCAT(A)———- ——————–1 d,b,a2 z,t执行计划上看，只需要做一次表扫描就可以了，但是这个函数是加密过的，执行计划并不能显示函数内部的操作。-----行列转换一数据格式一CARD_CODE          Q        BAL--------- ---------- ----------001                1         27001                2         10001                3         36001                4         97002                1         96002                2         12002                3         15002                4         32数据格式二CARD_CODE         Q1         Q2         Q3         Q4--------- ---------- ---------- ---------- ----------001               27         10         36         97002               96         12         15         32--格式一到格式二SELECT a.card_code, SUM(decode(a.q, 1, a.bal, 0)) q1, SUM(decode(a.q, 2, a.bal, 0)) q2,    SUM(decode(a.q, 3, a.bal, 0)) q3, SUM(decode(a.q, 4, a.bal, 0)) q4 FROM my_card a GROUP BY a.card_code ORDER BY 1;  --格式二到格式一SELECT t.card_code, t.rn q, decode(t.rn, 1, t.q1, 2, t.q2, 3, t.q3, 4, t.q4) bal FROM (SELECT a.*, b.rn      FROM my_card_two a,        (SELECT rownum rn          FROM dual         CONNECT BY rownum <= 4) b) t ORDER BY 1, 2;  ------行列转换二数据格式一CARD_CODE Q--------- ------------------------------------------------001       quarter_1001       quarter_2001       quarter_3001       quarter_4002       quarter_1002       quarter_2002       quarter_3002       quarter_4数据格式二CARD_CODE Q--------- -----------------------------002       quarter_1;quarter_2;quarter_3;quarter_4001       quarter_1;quarter_2;quarter_3;quarter_4--格式一到格式二SELECT t1.card_code, substr(MAX(sys_connect_by_path(t1.q, ';')), 2) q  FROM (SELECT a.card_code, a.q,                row_number() over(PARTITION BY a.card_code ORDER BY a.q) rn           FROM my_card_t3 a) t1 START WITH t1.rn = 1CONNECT BY t1.card_code = PRIOR t1.card_code           AND t1.rn - 1 = PRIOR t1.rn GROUP BY t1.card_code; --格式二到格式一SELECT t.card_code,    substr(t.q,        instr(';' || t.q, ';', 1, rn),        instr(t.q || ';', ';', 1, rn) - instr(';' || t.q, ';', 1, rn)) q FROM (SELECT a.card_code, a.q, b.rn      FROM my_card_t4 a,        (SELECT rownum rn          FROM dual         CONNECT BY rownum <= 100) b     WHERE instr(';' || a.q, ';', 1, rn) > 0) t ORDER BY 1, 2; 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