行列轉換包括以下六種情況：
*列轉行
*行轉列
*多列轉換成字串
*多行轉換成字串
*字串轉換成多列
*字串轉換成多行
下面分別進行舉例介紹。
首先宣告一點，有些例子需要如下10g及以後才有的知識：
a、掌握model子句
b、正規表示式
c、加強的層次查詢
討論的適用範圍只包括8i,9i,10g及以後版本。begin：
1、列轉行
未列轉行之前的效果如下：
列轉行的效果如下：
sql程式碼:
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–>適用範圍：8i,9i,10g及以後版本
sql程式碼：
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;
若空行不需要轉換，只需加一個where條件，
sql程式碼：
WHERE COLUMN IS NOT NULL
2).MODEL–>適用範圍：10g及以後
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表示欄位長度 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;
現在小分析一下上面這個查詢：
partition by (prd_type_id)指定結果是根據prd_type_id分割槽的。
dimension by (0 AS n)定義陣列的長度，這就意味著必須提供陣列索引才能訪問陣列中的單元。
measures ('xx' AS cn)表明陣列中的每個單元包含一個數量，同時表明陣列名為cn。
3).collection–>適用範圍：8i,9i,10g及以後版本
要建立一個物件和一個集合：
sql語句：
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、行轉列
未行轉列之前的效果如下：
行轉列的效果如下：
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–>適用範圍：8i,9i,10g及以後版本
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聚集函式也可以用sum、min、avg等其他聚集函式替代。
被指定的轉置列只能有一列，但固定的列可以有多列，請看下面的例子：
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;
這裡轉置列為empno，固定列為mgr，deptno。
還有一種行轉列的方式，就是相同組中的行值變為單個列值，但轉置的行值不變為列名：
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;
結果效果如下：
2)PL/SQL
適用範圍：8i,9i,10g及以後版本
這種對於行值不固定的情況可以使用。
下面是我寫的一個包，包中
p_rows_column_real用於前述的第一種不限定列的轉換；
p_rows_column用於前述的第二種不限定列的轉換。
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、多列轉換成字串
sql程式碼
CREATE TABLE t_col_str AS SELECT * FROM t_col_row; SELECT * FROM t_col_str;
用||或concat函式可以實現
SELECT * FROM t_col_str; SELECT ID, c1||','||c2||','||c3 AS c123 FROM t_col_str;
4、多行轉換成字串
未多行轉換成字串的效果：
多行轉換成字串的效果：
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–>適用範圍：8i,9i,10g及以後版本
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–>適用範圍：8i,9i,10g及以後版本
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–>適用範圍：10g及以後版本
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–>適用範圍：8i,9i,10g及以後版本
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–>適用範圍：10g及以後版本
這個函式預定義按','分隔字串，若要用其他符號分隔可以用，replace將','替換。
SELECT id, REPLACE(wmsys.wm_concat(col), ',', '/') FROM t_row_str GROUP BY id;
5、字串轉換成多列
其實際上就是一個字串拆分的問題。
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–>適用範圍：8i,9i,10g及以後版本
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–>正規表示式
適用範圍：10g及以後版本
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.字串轉換成多行
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
適用範圍：8i,9i,10g及以後版本
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;
適用範圍：10g及以後版本
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;
適用範圍：10g及以後版本
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
適用範圍：10g及以後版本
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
適用範圍：10g及以後版本
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
適用範圍：10g及以後版本
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;