Oracle行转列的写法
Oracle行转列的写法（转贴）：
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;
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;
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;
