行列转换包括以下六种情况：
*列转行
*行转列
*多列转换成字符串
*多行转换成字符串
*字符串转换成多列
*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。begin：
1、列转行
未列转行之前的效果如下：
列转行的效果如下：
sql代码:
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
sql代码：
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，
sql代码：
WHERE COLUMN IS NOT NULL
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) --xx、yyy表示字段长度 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;
现在小分析一下上面这个查询：
partition by (prd_type_id)指定结果是根据prd_type_id分区的。
dimension by (0 AS n)定义数组的长度，这就意味着必须提供数组索引才能访问数组中的单元。
measures ('xx' AS cn)表明数组中的每个单元包含一个数量，同时表明数组名为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：
sql语句：
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;
2、行转列
未行转列之前的效果如下：
行转列的效果如下：
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;
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 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.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：
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;
结果效果如下：
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
sql代码
CREATE TABLE t_col_str AS SELECT * FROM t_col_row; SELECT * FROM t_col_str;
用||或concat函数可以实现
SELECT * FROM t_col_str; SELECT ID, c1||','||c2||','||c3 AS c123 FROM t_col_str;
4、多行转换成字符串
未多行转换成字符串的效果：
多行转换成字符串的效果：
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;
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;
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;
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;
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;
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), ',', '/') FROM t_row_str GROUP BY id;
5、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;
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;
2)regexp_substr–>正则表达式
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;
6.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;
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;
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;
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;
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;
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)) INCREMENT 1 ] = rtrim(regexp_substr( cv[0],'.*?'||',',1,cv(p)),',')) ORDER BY 1,2;