Oracle行列转换的一点小总结(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;

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;

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;

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;

end.

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