Oracle 行列转换包括以下六种情况：(一)(二)(三)

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

 

首先声明，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

1、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;

 

 

1).  UNION ALL: 适用范围：8i,9i,10g及以后版本

SELECT id, 'c1' cn, c1 cv  FROM t_col_rowUNION ALL　　SELECT id, 'c2' cn, c2 cv   FROM t_col_rowUNION 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). MODEL
适用范围：10g及以后

SELECT id, cn, cv FROM t_col_rowMODELRETURN UPDATED ROWSPARTITION 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;

 

 

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))) tORDER BY 1, 2;

 

 

2、行转列

CREATE TABLE t_row_col ASSELECT id, 'c1' cn, c1 cv　　FROM t_col_rowUNION ALLSELECT id, 'c2' cn, c2 cv　　FROM t_col_rowUNION ALLSELECT id, 'c3' cn, c3 cv FROM t_col_row; SELECT * FROM t_row_col ORDER BY 1,2;

 

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_colGROUP BY idORDER BY 1;

 

MAX聚集函数也可以用sum、min、avg等其他聚集函数替代。

　sign()函数根据某个值是0、正数还是负数，分别返回0、1、-1
　　用sign和decode来完成比较字段大小来区某个字段
　　select decode(sign(字段1-字段2),-1,字段3,字段4) from dual;

 

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 scott.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 scott.empWHERE mgr IN (7566, 7698)   AND deptno IN (20, 30)GROUP BY mgr, deptnoORDER 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;

 

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;/ 

 

3.多列转换成字符串

 

CREATE TABLE t_col_str ASSELECT * 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;

 

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 c123FROM t_col_str;