I have a table named student_info in my database.There are multiple columns out of which two columns store comma separated values
class_id student marks
----------------------------------------------
1 tom,jam,tim 55,65,75
2 rim,gum,ram 33,66,77
i want the output to be as follows
class_id student marks
------------------------------------------------
1 tom 55
1 tom 65
1 tom 75
1 jam 55
1 jam 65
1 jam 75
1 tim 55
1 tim 65
1 tim 75
my Query as below
SELECT student_id,TRIM(REGEXP_SUBSTR(student, '[^,]+', 1, level)) student_name
FROM STUDENT_INFO
CONNECT BY level <= REGEXP_COUNT(student, '[^,]+')
AND PRIOR student = student AND marks = marks
AND PRIOR DBMS_RANDOM.VALUE IS NOT NULL
with the above query i can get the output as below
class_id student_name marks
------------------------------
1 tom 55,65,75
1 jam 55,65,75
1 tim 55,65,75
How to achieve the desired output ?any suggestions?
It would be lot easier to normalize table than finding complicated methods to convert csv to rows.
In this case, you can use this:
with t(class_id, student, marks) as (
select 1, 'tom,jam,tim', '55,65,75' from dual union all
select 2, 'rim,gum,ram', '33,66,77' from dual
)
select
t.class_id,
regexp_substr(student,'[^,]+',1,x.column_value) student,
regexp_substr(marks,'[^,]+',1,y.column_value) marks
from t, table(
cast(
multiset(
select level
from dual
connect by level <= regexp_count(t.student,',') + 1
) as sys.odcinumberlist
)
)x,table(
cast(
multiset(
select level
from dual
connect by level <= regexp_count(t.marks,',') + 1
) as sys.odcinumberlist
)
)y
Produces:
+----------+------------+-------+
| CLASS_ID | STUDENT | MARKS |
+----------+------------+-------+
| 1 | tom | 55 |
+----------+------------+-------+
| 1 | tom | 65 |
+----------+------------+-------+
| 1 | tom | 75 |
+----------+------------+-------+
| 1 | jam | 55 |
+----------+------------+-------+
| 1 | jam | 65 |
+----------+------------+-------+
| 1 | jam | 75 |
+----------+------------+-------+
| 1 | tim | 55 |
+----------+------------+-------+
| 1 | tim | 65 |
+----------+------------+-------+
| 1 | tim | 75 |
+----------+------------+-------+
| 2 | rim | 33 |
+----------+------------+-------+
| 2 | rim | 66 |
+----------+------------+-------+
| 2 | rim | 77 |
+----------+------------+-------+
| 2 | gum | 33 |
+----------+------------+-------+
| 2 | gum | 66 |
+----------+------------+-------+
| 2 | gum | 77 |
+----------+------------+-------+
| 2 | ram | 33 |
+----------+------------+-------+
| 2 | ram | 66 |
+----------+------------+-------+
| 2 | ram | 77 |
+----------+------------+-------+
Hierarchical Query:
Use correlated-hierarchical queries to find the sub-strings once and then apply the cross product to join them:
SELECT class_id,
s.COLUMN_VALUE AS student,
m.COLUMN_VALUE AS mark
FROM table_name t,
TABLE(
CAST(
MULTISET(
SELECT REGEXP_SUBSTR( t.students, '[^,]+', 1, LEVEL )
FROM DUAL
CONNECT BY LEVEL <= REGEXP_COUNT( t.students, '[^,]+' )
) AS SYS.ODCIVARCHAR2LIST
)
) s,
TABLE(
CAST(
MULTISET(
SELECT TO_NUMBER( REGEXP_SUBSTR( t.marks, '[^,]+', 1, LEVEL ) )
FROM DUAL
CONNECT BY LEVEL <= REGEXP_COUNT( t.marks, '[^,]+' )
) AS SYS.ODCIVARCHAR2LIST
)
) m
Output:
CLASS_ID STUDENT MARKS
-------- ------- -----
1 tom 55
1 tom 65
1 tom 75
1 jam 55
1 jam 65
1 jam 75
1 tim 55
1 tim 65
1 tim 75
2 rim 33
2 rim 66
2 rim 77
2 gum 33
2 gum 66
2 gum 77
2 ram 33
2 ram 66
2 ram 77
Recursive Subquery Factoring:
WITH cte ( class_id, student, marks, s, m, smax, mmax ) AS (
SELECT class_id,
student,
marks,
1,
1,
REGEXP_COUNT( student, '[^,]+' ),
REGEXP_COUNT( marks, '[^,]+' )
FROM table_name
UNION ALL
SELECT class_id,
student,
marks,
CASE WHEN m = mmax THEN s + 1 ELSE s END,
CASE WHEN m = mmax THEN 1 ELSE m + 1 END,
smax,
mmax
FROM cte
WHERE m < mmax OR s < smax
)
SELECT class_id,
REGEXP_SUBSTR( student, '[^,]+', 1, s ) AS student,
TO_NUMBER( REGEXP_SUBSTR( mark, '[^,]+', 1, m ) ) AS mark
FROM cte;
Using ora:tokenizer
with t(class_id, student, marks) as (
select 1, 'tom,jam,tim', '55,65,75' from dual union all
select 2, 'rim,gum,ram', '33,66,77' from dual
)
select class_id,new_student,new_marks from t
,xmltable('for $i in ora:tokenize($students,",") return $i' passing student as "students" columns new_student varchar2(20) path '.')
,xmltable('for $j in ora:tokenize($marks,",") return $j' passing marks as "marks" columns new_marks varchar2(20) path '.')
try this
with temp as
(
select 1 class_id , 'tom,jam,tim' student, '55,65,75' marks from dual
union all
select 2 class_id , 'rim,gum,ram' student, '33,66,77' marks from dual
)
select distinct
t.class_id,
trim(regexp_substr(t.student, '[^,]+', 1, students.column_value)) as students,
trim(regexp_substr(t.marks, '[^,]+', 1, marks.column_value)) as marks
from
temp t,
table(cast(multiset(select level from dual connect by level <= length (regexp_replace(t.student, '[^,]+')) + 1) as sys.OdciNumberList)) students,
table(cast(multiset(select level from dual connect by level <= length (regexp_replace(t.marks, '[^,]+')) + 1) as sys.OdciNumberList)) marks
order by class_id;
来源：https://stackoverflow.com/questions/41699487/convert-comma-separated-values-to-rows-in-oracle