概述
最近论坛很多人提的问题都与行列转换有关系，所以我对行列转换的相关知识做了一个总结，希望对大家有所帮助，同时有何错疏，恳请大家指出，我也是在写作过程中学习，算是一起和大家学习吧！
行列转换包括以下六种情况：
1)
列转行
2)
行转列
3)
多列转换成字符串
4)
多行转换成字符串
5)
字符串转换成多列
6)
字符串转换成多行
下面分别进行举例介绍。
首先声明一点，有些例子需要如下10g及以后才有的知识：
A.
掌握model子句
B.
正则表达式
C.
加强的层次查询
讨论的适用范围只包括8i,9i,10g及以后版本。
2.
列转行
CREATE TABLE t_col_row(
ID INT,
c1 VARCHAR2(10),
c2 VARCHAR2(10),
c3 VARCHAR2(10));
INSERT INTO t_col_row VALUES (1, 'v11', 'v21', 'v31');
INSERT INTO t_col_row VALUES (2, 'v12', 'v22', NULL);
INSERT INTO t_col_row VALUES (3, 'v13', NULL, 'v33');
INSERT INTO t_col_row VALUES (4, NULL, 'v24', 'v34');
INSERT INTO t_col_row VALUES (5, 'v15', NULL, NULL);
INSERT INTO t_col_row VALUES (6, NULL, NULL, 'v35');
INSERT INTO t_col_row VALUES (7, NULL, NULL, NULL);
COMMIT;
SELECT * FROM t_col_row;
2.1
UNION ALL
适用范围：8i,9i,10g及以后版本
SELECT id, 'c1' cn, c1 cv
FROM t_col_row
UNION ALL
SELECT id, 'c2' cn, c2 cv
FROM t_col_row
UNION ALL
SELECT id, 'c3' cn, c3 cv FROM t_col_row;
若空行不需要转换，只需加一个where条件，
WHERE COLUMN IS NOT NULL 即可。
2.2
MODEL
适用范围：10g及以后
SELECT id, cn, cv FROM t_col_row
MODEL
RETURN UPDATED ROWS
PARTITION BY (ID)
DIMENSION BY (0 AS n)
MEASURES ('xx' AS cn,'yyy' AS cv,c1,c2,c3)
RULES UPSERT ALL
(
cn[1] = 'c1',
cn[2] = 'c2',
cn[3] = 'c3',
cv[1] = c1[0],
cv[2] = c2[0],
cv[3] = c3[0]
)
ORDER BY ID,cn;
2.3
COLLECTION
适用范围：8i,9i,10g及以后版本
要创建一个对象和一个集合：
CREATE TYPE cv_pair AS OBJECT(cn VARCHAR2(10),cv VARCHAR2(10));
CREATE TYPE cv_varr AS VARRAY(8) OF cv_pair;
SELECT id, t.cn AS cn, t.cv AS cv
FROM t_col_row,
TABLE(cv_varr(cv_pair('c1', t_col_row.c1),
cv_pair('c2', t_col_row.c2),
cv_pair('c3', t_col_row.c3))) t
ORDER BY 1, 2;
3.
行转列
CREATE TABLE t_row_col AS
SELECT id, 'c1' cn, c1 cv
FROM t_col_row
UNION ALL
SELECT id, 'c2' cn, c2 cv
FROM t_col_row
UNION ALL
SELECT id, 'c3' cn, c3 cv FROM t_col_row;
SELECT * FROM t_row_col ORDER BY 1,2;
3.1
AGGREGATE FUNCTION
适用范围：8i,9i,10g及以后版本
SELECT id,
MAX(decode(cn, 'c1', cv, NULL)) AS c1,
MAX(decode(cn, 'c2', cv, NULL)) AS c2,
MAX(decode(cn, 'c3', cv, NULL)) AS c3
FROM t_row_col
GROUP BY id
ORDER BY 1;
MAX聚集函数也可以用sum、min、avg等其他聚集函数替代。
被指定的转置列只能有一列，但固定的列可以有多列，请看下面的例子：
SELECT mgr, deptno, empno, ename FROM emp ORDER BY 1, 2;
SELECT mgr,
deptno,
MAX(decode(empno, '7788', ename, NULL)) "7788",
MAX(decode(empno, '7902', ename, NULL)) "7902",
MAX(decode(empno, '7844', ename, NULL)) "7844",
MAX(decode(empno, '7521', ename, NULL)) "7521",
MAX(decode(empno, '7900', ename, NULL)) "7900",
MAX(decode(empno, '7499', ename, NULL)) "7499",
MAX(decode(empno, '7654', ename, NULL)) "7654"
FROM emp
WHERE mgr IN (7566, 7698)
AND deptno IN (20, 30)
GROUP BY mgr, deptno
ORDER BY 1, 2;
这里转置列为empno，固定列为mgr，deptno。
还有一种行转列的方式，就是相同组中的行值变为单个列值，但转置的行值不变为列名：
ID CN_1 CV_1 CN_2 CV_2 CN_3 CV_3
1 c1 v11 c2 v21 c3 v31
2 c1 v12 c2 v22 c3
3 c1 v13 c2 c3 v33
4 c1 c2 v24 c3 v34
5 c1 v15 c2 c3
6 c1 c2 c3 v35
7 c1 c2 c3
这种情况可以用分析函数实现：
SELECT id,
MAX(decode(rn, 1, cn, NULL)) cn_1,
MAX(decode(rn, 1, cv, NULL)) cv_1,
MAX(decode(rn, 2, cn, NULL)) cn_2,
MAX(decode(rn, 2, cv, NULL)) cv_2,
MAX(decode(rn, 3, cn, NULL)) cn_3,
MAX(decode(rn, 3, cv, NULL)) cv_3
FROM (SELECT id,
cn,
cv,
row_number() over(PARTITION BY id ORDER BY cn, cv) rn
FROM t_row_col)
GROUP BY ID;
3.2
PL/SQL
适用范围：8i,9i,10g及以后版本
这种对于行值不固定的情况可以使用。
下面是我写的一个包，包中
p_rows_column_real用于前述的第一种不限定列的转换；
p_rows_column用于前述的第二种不限定列的转换。
CREATE OR REPLACE PACKAGE pkg_dynamic_rows_column AS
TYPE refc IS REF CURSOR;
PROCEDURE p_print_sql(p_txt VARCHAR2);
FUNCTION f_split_str(p_str VARCHAR2, p_division VARCHAR2, p_seq INT)
RETURN VARCHAR2;
PROCEDURE p_rows_column(p_table IN VARCHAR2,
p_keep_cols IN VARCHAR2,
p_pivot_cols IN VARCHAR2,
p_where IN VARCHAR2 DEFAULT NULL,
p_refc IN OUT refc);
PROCEDURE p_rows_column_real(p_table IN VARCHAR2,
p_keep_cols IN VARCHAR2,
p_pivot_col IN VARCHAR2,
p_pivot_val IN VARCHAR2,
p_where IN VARCHAR2 DEFAULT NULL,
p_refc IN OUT refc);
END;
/
CREATE OR REPLACE PACKAGE BODY pkg_dynamic_rows_column AS
PROCEDURE p_print_sql(p_txt VARCHAR2) IS
v_len INT;
BEGIN
v_len := length(p_txt);
FOR i IN 1 .. v_len / 250 + 1 LOOP
dbms_output.put_line(substrb(p_txt, (i - 1) * 250 + 1, 250));
END LOOP;
END;
FUNCTION f_split_str(p_str VARCHAR2, p_division VARCHAR2, p_seq INT)
RETURN VARCHAR2 IS
v_first INT;
v_last INT;
BEGIN
IF p_seq < 1 THEN
RETURN NULL;
END IF;
IF p_seq = 1 THEN
IF instr(p_str, p_division, 1, p_seq) = 0 THEN
RETURN p_str;
ELSE
RETURN substr(p_str, 1, instr(p_str, p_division, 1) - 1);
END IF;
ELSE
v_first := instr(p_str, p_division, 1, p_seq - 1);
v_last := instr(p_str, p_division, 1, p_seq);
IF (v_last = 0) THEN
IF (v_first > 0) THEN
RETURN substr(p_str, v_first + 1);
ELSE
RETURN NULL;
END IF;
ELSE
RETURN substr(p_str, v_first + 1, v_last - v_first - 1);
END IF;
END IF;
END f_split_str;
PROCEDURE p_rows_column(p_table IN VARCHAR2,
p_keep_cols IN VARCHAR2,
p_pivot_cols IN VARCHAR2,
p_where IN VARCHAR2 DEFAULT NULL,
p_refc IN OUT refc) IS
v_sql VARCHAR2(4000);
TYPE v_keep_ind_by IS TABLE OF VARCHAR2(4000) INDEX BY BINARY_INTEGER;
v_keep v_keep_ind_by;
TYPE v_pivot_ind_by IS TABLE OF VARCHAR2(4000) INDEX BY BINARY_INTEGER;
v_pivot v_pivot_ind_by;
v_keep_cnt INT;
v_pivot_cnt INT;
v_max_cols INT;
v_partition VARCHAR2(4000);
v_partition1 VARCHAR2(4000);
v_partition2 VARCHAR2(4000);
BEGIN
v_keep_cnt := length(p_keep_cols) - length(REPLACE(p_keep_cols, ',')) + 1;
v_pivot_cnt := length(p_pivot_cols) -
length(REPLACE(p_pivot_cols, ',')) + 1;
FOR i IN 1 .. v_keep_cnt LOOP
v_keep(i) := f_split_str(p_keep_cols, ',', i);
END LOOP;
FOR j IN 1 .. v_pivot_cnt LOOP
v_pivot(j) := f_split_str(p_pivot_cols, ',', j);
END LOOP;
v_sql := 'select max(count(*)) from ' || p_table || ' group by ';
FOR i IN 1 .. v_keep.LAST LOOP
v_sql := v_sql || v_keep(i) || ',';
END LOOP;
v_sql := rtrim(v_sql, ',');
EXECUTE IMMEDIATE v_sql
INTO v_max_cols;
v_partition := 'select ';
FOR x IN 1 .. v_keep.COUNT LOOP
v_partition1 := v_partition1 || v_keep(x) || ',';
END LOOP;
FOR y IN 1 .. v_pivot.COUNT LOOP
v_partition2 := v_partition2 || v_pivot(y) || ',';
END LOOP;
v_partition1 := rtrim(v_partition1, ',');
v_partition2 := rtrim(v_partition2, ',');
v_partition := v_partition || v_partition1 || ',' || v_partition2 ||
', row_number() over (partition by ' || v_partition1 ||
' order by ' || v_partition2 || ') rn from ' || p_table;
v_partition := rtrim(v_partition, ',');
v_sql := 'select ';
FOR i IN 1 .. v_keep.COUNT LOOP
v_sql := v_sql || v_keep(i) || ',';
END LOOP;
FOR i IN 1 .. v_max_cols LOOP
FOR j IN 1 .. v_pivot.COUNT LOOP
v_sql := v_sql || ' max(decode(rn,' || i || ',' || v_pivot(j) ||
',null))' || v_pivot(j) || '_' || i || ',';
END LOOP;
END LOOP;
IF p_where IS NOT NULL THEN
v_sql := rtrim(v_sql, ',') || ' from (' || v_partition || ' ' ||
p_where || ') group by ';
ELSE
v_sql := rtrim(v_sql, ',') || ' from (' || v_partition ||
') group by ';
END IF;
FOR i IN 1 .. v_keep.COUNT LOOP
v_sql := v_sql || v_keep(i) || ',';
END LOOP;
v_sql := rtrim(v_sql, ',');
p_print_sql(v_sql);
OPEN p_refc FOR v_sql;
EXCEPTION
WHEN OTHERS THEN
OPEN p_refc FOR
SELECT 'x' FROM dual WHERE 0 = 1;
END;
PROCEDURE p_rows_column_real(p_table IN VARCHAR2,
p_keep_cols IN VARCHAR2,
p_pivot_col IN VARCHAR2,
p_pivot_val IN VARCHAR2,
p_where IN VARCHAR2 DEFAULT NULL,
p_refc IN OUT refc) IS
v_sql VARCHAR2(4000);
TYPE v_keep_ind_by IS TABLE OF VARCHAR2(4000) INDEX BY BINARY_INTEGER;
v_keep v_keep_ind_by;
TYPE v_pivot_ind_by IS TABLE OF VARCHAR2(4000) INDEX BY BINARY_INTEGER;
v_pivot v_pivot_ind_by;
v_keep_cnt INT;
v_group_by VARCHAR2(2000);
BEGIN
v_keep_cnt := length(p_keep_cols) - length(REPLACE(p_keep_cols, ',')) + 1;
FOR i IN 1 .. v_keep_cnt LOOP
v_keep(i) := f_split_str(p_keep_cols, ',', i);
END LOOP;
v_sql := 'select ' || 'cast(' || p_pivot_col ||
' as varchar2(200)) as ' || p_pivot_col || ' from ' || p_table ||
' group by ' || p_pivot_col;
EXECUTE IMMEDIATE v_sql BULK COLLECT
INTO v_pivot;
FOR i IN 1 .. v_keep.COUNT LOOP
v_group_by := v_group_by || v_keep(i) || ',';
END LOOP;
v_group_by := rtrim(v_group_by, ',');
v_sql := 'select ' || v_group_by || ',';
FOR x IN 1 .. v_pivot.COUNT LOOP
v_sql := v_sql || ' max(decode(' || p_pivot_col || ',' || chr(39) ||
v_pivot(x) || chr(39) || ',' || p_pivot_val ||
',null)) as "' || v_pivot(x) || '",';
END LOOP;
v_sql := rtrim(v_sql, ',');
IF p_where IS NOT NULL THEN
v_sql := v_sql || ' from ' || p_table || p_where || ' group by ' ||
v_group_by;
ELSE
v_sql := v_sql || ' from ' || p_table || ' group by ' || v_group_by;
END IF;
p_print_sql(v_sql);
OPEN p_refc FOR v_sql;
EXCEPTION
WHEN OTHERS THEN
OPEN p_refc FOR
SELECT 'x' FROM dual WHERE 0 = 1;
END;
END;
/
4.
多列转换成字符串
CREATE TABLE t_col_str AS
SELECT * FROM t_col_row;
这个比较简单，用||或concat函数可以实现：
SELECT concat('a','b') FROM dual;
4.1
|| OR CONCAT
适用范围：8i,9i,10g及以后版本
SELECT * FROM t_col_str;
SELECT ID,c1||','||c2||','||c3 AS c123
FROM t_col_str;
5.
多行转换成字符串
CREATE TABLE t_row_str(
ID INT,
col VARCHAR2(10));
INSERT INTO t_row_str VALUES(1,'a');
INSERT INTO t_row_str VALUES(1,'b');
INSERT INTO t_row_str VALUES(1,'c');
INSERT INTO t_row_str VALUES(2,'a');
INSERT INTO t_row_str VALUES(2,'d');
INSERT INTO t_row_str VALUES(2,'e');
INSERT INTO t_row_str VALUES(3,'c');
COMMIT;
SELECT * FROM t_row_str;
5.1
MAX + DECODE
适用范围：8i,9i,10g及以后版本
SELECT id,
MAX(decode(rn, 1, col, NULL)) ||
MAX(decode(rn, 2, ',' || col, NULL)) ||
MAX(decode(rn, 3, ',' || col, NULL)) str
FROM (SELECT id,
col,
row_number() over(PARTITION BY id ORDER BY col) AS rn
FROM t_row_str) t
GROUP BY id
ORDER BY 1;
5.2
ROW_NUMBER + LEAD
适用范围：8i,9i,10g及以后版本
SELECT id, str
FROM (SELECT id,
row_number() over(PARTITION BY id ORDER BY col) AS rn,
col || lead(',' || col, 1) over(PARTITION BY id ORDER BY col) ||
lead(',' || col, 2) over(PARTITION BY id ORDER BY col) ||
lead(',' || col, 3) over(PARTITION BY id ORDER BY col) AS str
FROM t_row_str)
WHERE rn = 1
ORDER BY 1;
5.3
MODEL
适用范围：10g及以后版本
SELECT id, substr(str, 2) str FROM t_row_str
MODEL
RETURN UPDATED ROWS
PARTITION BY(ID)
DIMENSION BY(row_number() over(PARTITION BY ID ORDER BY col) AS rn)
MEASURES (CAST(col AS VARCHAR2(20)) AS str)
RULES UPSERT
ITERATE(3) UNTIL( presentv(str[iteration_number+2],1,0)=0)
(str[0] = str[0] || ',' || str[iteration_number+1])
ORDER BY 1;
5.4
SYS_CONNECT_BY_PATH
适用范围：8i,9i,10g及以后版本
SELECT t.id id, MAX(substr(sys_connect_by_path(t.col, ','), 2)) str
FROM (SELECT id, col, row_number() over(PARTITION BY id ORDER BY col) rn
FROM t_row_str) t
START WITH rn = 1
CONNECT BY rn = PRIOR rn + 1
AND id = PRIOR id
GROUP BY t.id;
适用范围：10g及以后版本
SELECT t.id id, substr(sys_connect_by_path(t.col, ','), 2) str
FROM (SELECT id, col, row_number() over(PARTITION BY id ORDER BY col) rn
FROM t_row_str) t
WHERE connect_by_isleaf = 1
START WITH rn = 1
CONNECT BY rn = PRIOR rn + 1
AND id = PRIOR id;
5.5
WMSYS.WM_CONCAT
适用范围：10g及以后版本
这个函数预定义按','分隔字符串，若要用其他符号分隔可以用，replace将','替换。
SELECT id, REPLACE(wmsys.wm_concat(col), ',', '/') str
FROM t_row_str
GROUP BY id;
6.
字符串转换成多列
其实际上就是一个字符串拆分的问题。
CREATE TABLE t_str_col AS
SELECT ID,c1||','||c2||','||c3 AS c123
FROM t_col_str;
SELECT * FROM t_str_col;
6.1
SUBSTR + INSTR
适用范围：8i,9i,10g及以后版本
SELECT id,
c123,
substr(c123, 1, instr(c123 || ',', ',', 1, 1) - 1) c1,
substr(c123,
instr(c123 || ',', ',', 1, 1) + 1,
instr(c123 || ',', ',', 1, 2) - instr(c123 || ',', ',', 1, 1) - 1) c2,
substr(c123,
instr(c123 || ',', ',', 1, 2) + 1,
instr(c123 || ',', ',', 1, 3) - instr(c123 || ',', ',', 1, 2) - 1) c3
FROM t_str_col
ORDER BY 1;
6.2
REGEXP_SUBSTR
适用范围：10g及以后版本
SELECT id,
c123,
rtrim(regexp_substr(c123 || ',', '.*?' || ',', 1, 1), ',') AS c1,
rtrim(regexp_substr(c123 || ',', '.*?' || ',', 1, 2), ',') AS c2,
rtrim(regexp_substr(c123 || ',', '.*?' || ',', 1, 3), ',') AS c3
FROM t_str_col
ORDER BY 1;
7.
字符串转换成多行
CREATE TABLE t_str_row AS
SELECT id,
MAX(decode(rn, 1, col, NULL)) ||
MAX(decode(rn, 2, ',' || col, NULL)) ||
MAX(decode(rn, 3, ',' || col, NULL)) str
FROM (SELECT id,
col,
row_number() over(PARTITION BY id ORDER BY col) AS rn
FROM t_row_str) t
GROUP BY id
ORDER BY 1;
SELECT * FROM t_str_row;
7.1
UNION ALL
适用范围：8i,9i,10g及以后版本
SELECT id, 1 AS p, substr(str, 1, instr(str || ',', ',', 1, 1) - 1) AS cv
FROM t_str_row
UNION ALL
SELECT id,
2 AS p,
substr(str,
instr(str || ',', ',', 1, 1) + 1,
instr(str || ',', ',', 1, 2) - instr(str || ',', ',', 1, 1) - 1) AS cv
FROM t_str_row
UNION ALL
SELECT id,
3 AS p,
substr(str,
instr(str || ',', ',', 1, 1) + 1,
instr(str || ',', ',', 1, 2) - instr(str || ',', ',', 1, 1) - 1) AS cv
FROM t_str_row
ORDER BY 1, 2;
适用范围：10g及以后版本
SELECT id, 1 AS p, rtrim(regexp_substr(str||',', '.*?' || ',', 1, 1), ',') AS cv
FROM t_str_row
UNION ALL
SELECT id, 2 AS p, rtrim(regexp_substr(str||',', '.*?' || ',', 1, 2), ',') AS cv
FROM t_str_row
UNION ALL
SELECT id, 3 AS p, rtrim(regexp_substr(str||',', '.*?' || ',',1,3), ',') AS cv
FROM t_str_row
ORDER BY 1, 2;
7.2
VARRAY
适用范围：8i,9i,10g及以后版本
要创建一个可变数组：
CREATE OR REPLACE TYPE ins_seq_type IS VARRAY(8) OF NUMBER;
SELECT * FROM TABLE(ins_seq_type(1, 2, 3, 4, 5));
SELECT t.id,
c.column_value AS p,
substr(t.ca,
instr(t.ca, ',', 1, c.column_value) + 1,
instr(t.ca, ',', 1, c.column_value + 1) -
(instr(t.ca, ',', 1, c.column_value) + 1)) AS cv
FROM (SELECT id,
',' || str || ',' AS ca,
length(str || ',') - nvl(length(REPLACE(str, ',')), 0) AS cnt
FROM t_str_row) t
INNER JOIN TABLE(ins_seq_type(1, 2, 3)) c ON c.column_value <=
t.cnt
ORDER BY 1, 2;
7.3
SEQUENCE SERIES
这类方法主要是要产生一个连续的整数列，产生连续整数列的方法有很多，主要有：
CONNECT BY,ROWNUM+all_objects,CUBE等。
适用范围：8i,9i,10g及以后版本
SELECT t.id,
c.lv AS p,
substr(t.ca,
instr(t.ca, ',', 1, c.lv) + 1,
instr(t.ca, ',', 1, c.lv + 1) -
(instr(t.ca, ',', 1, c.lv) + 1)) AS cv
FROM (SELECT id,
',' || str || ',' AS ca,
length(str || ',') - nvl(length(REPLACE(str, ',')), 0) AS cnt
FROM t_str_row) t,
(SELECT LEVEL lv FROM dual CONNECT BY LEVEL <= 5) c
WHERE c.lv <= t.cnt
ORDER BY 1, 2;
SELECT t.id,
c.rn AS p,
substr(t.ca,
instr(t.ca, ',', 1, c.rn) + 1,
instr(t.ca, ',', 1, c.rn + 1) -
(instr(t.ca, ',', 1, c.rn) + 1)) AS cv
FROM (SELECT id,
',' || str || ',' AS ca,
length(str || ',') - nvl(length(REPLACE(str, ',')), 0) AS cnt
FROM t_str_row) t,
(SELECT rownum rn FROM all_objects WHERE rownum <= 5) c
WHERE c.rn <= t.cnt
ORDER BY 1, 2;
SELECT t.id,
c.cb AS p,
substr(t.ca,
instr(t.ca, ',', 1, c.cb) + 1,
instr(t.ca, ',', 1, c.cb + 1) -
(instr(t.ca, ',', 1, c.cb) + 1)) AS cv
FROM (SELECT id,
',' || str || ',' AS ca,
length(str || ',') - nvl(length(REPLACE(str, ',')), 0) AS cnt
FROM t_str_row) t,
(SELECT rownum cb FROM (SELECT 1 FROM dual GROUP BY CUBE(1, 2))) c
WHERE c.cb <= t.cnt
ORDER BY 1, 2;
适用范围：10g及以后版本
SELECT t.id,
c.lv AS p,
rtrim(regexp_substr(t.str || ',', '.*?' || ',', 1, c.lv), ',') AS cv
FROM (SELECT id,
str,
length(regexp_replace(str || ',', '[^' || ',' || ']', NULL)) AS cnt
FROM t_str_row) t
INNER JOIN (SELECT LEVEL lv FROM dual CONNECT BY LEVEL <= 5) c ON c.lv <= t.cnt
ORDER BY 1, 2;
7.4
HIERARCHICAL + DBMS_RANDOM
适用范围：10g及以后版本
SELECT id,
LEVEL AS p,
rtrim(regexp_substr(str || ',', '.*?' || ',', 1, LEVEL), ',') AS cv
FROM t_str_row
CONNECT BY id = PRIOR id
AND PRIOR dbms_random.VALUE IS NOT NULL
AND LEVEL <=
length(regexp_replace(str || ',', '[^' || ',' || ']', NULL))
ORDER BY 1, 2;
7.5
HIERARCHICAL + CONNECT_BY_ROOT
适用范围：10g及以后版本
SELECT id,
LEVEL AS p,
rtrim(regexp_substr(str || ',', '.*?' || ',', 1, LEVEL), ',') AS cv
FROM t_str_row
CONNECT BY id = connect_by_root id
AND LEVEL <=
length(regexp_replace(str || ',', '[^' || ',' || ']', NULL))
ORDER BY 1, 2;
7.6
MODEL
适用范围：10g及以后版本
SELECT id, p, cv FROM t_str_row
MODEL
RETURN UPDATED ROWS
PARTITION BY(ID)
DIMENSION BY( 0 AS p)
MEASURES( str||',' AS cv)
RULES UPSERT
(cv
[ FOR p
FROM 1 TO length(regexp_replace(cv[0],'[^'||','||']',null))
*****************************************************************************************************************************************************************************************
*****************************************************************************************************************************************************************************************
1、固定列数的行列转换
如
student subject grade
--------- ---------- --------
student1 语文 80
student1 数学 70
student1 英语 60
student2 语文 90
student2 数学 80
student2 英语 100
……
转换为
语文 数学 英语
student1 80 70 60
student2 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 table
group 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 VARCHAR2
IS
Col_c2 VARCHAR2(4000);
BEGIN
FOR cur IN (SELECT c2 FROM t WHERE c1=tmp_c1) LOOP
Col_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 NULL
CONNECT BY rn1 = PRIOR rn
GROUP 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 CALLCOUNT
1 2005-08-08 40
1 2005-08-07 6
2 2005-08-08 77
3 2005-08-09 33
3 2005-08-08 9
3 2005-08-07 21
转置后：
CALLDATE CallCount1 CallCount2 CallCount3
------------ ---------- ---------- ----------
2005-08-09 0 0 33
2005-08-08 40 77 9
2005-08-07 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_getrecord
IS
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.myrctype
IS
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 33
2005-08-08 40 77 9
2005-08-07 6 0 21