JSON elements parsing into oracle column - json

Question

I have a oracle table where one column has JSON data. I need to extract two elements from the data and want to display as column.
I am adding JSON data as a code sample to test.
create table TEST_TABLE
(id number,
importdata clob);
insert into TEST_TABLE values (100,'{"ClassId":30074,"Attributes":[{"Name":"TYPE-SPEC","Value":"SJ;3;1"},{"Name":"HREF","Value":"-1"},{"Name":"HMETHOD","Value":"96"},{"Name":"GEO_METHOD","Value":"96"},{"Name":"HPRCSN","Value":2.7676}]}');
insert into TEST_TABLE values (101,'{"ClassId":30074,"Attributes":[{"Name":"TYPE-SPEC","Value":"SJ;3;1"},{"Name":"HREF","Value":"-1"},{"Name":"HMETHOD","Value":"96"},{"Name":"HPRCSN","Value":3.04}]}');
insert into TEST_TABLE values (102,'{"ClassId":30074,"Attributes":[{"Name":"TYPE-SPEC","Value":"SJ;3;1"},{"Name":"HREF","Value":"-1"},{"Name":"HMETHOD","Value":"96"},{"Name":"GEO_METHOD","Value":"96"},{"Name":"HPRCSN","Value":77.1814}]}');
insert into TEST_TABLE values (103,'{"ClassId":30074,"Attributes":[{"Name":"TYPE-SPEC","Value":"SJ;3;1"},{"Name":"HREF","Value":"-1"},{"Name":"HMETHOD","Value":"96"},{"Name":"GEO_METHOD","Value":"-1"},{"Name":"HPRCSN","Value":3.1121}]}');
insert into TEST_TABLE values (105,'{"ClassId":32000,"Attributes":[{"Name":"ID","Value":"69804"},{"Name":"HREF","Value":"-1"},{"Name":"HPRCSN","Value":"5"}]},{"Name":"HMETHOD","Value":"96"} ');
insert into TEST_TABLE values (106,'{"ClassId":32000,"Attributes":[{"Name":"ID","Value":"73576"},{"Name":"HREF","Value":"-1"},{"Name":"HPRCSN","Value":"5"}]},{"Name":"HMETHOD","Value":"96"}]} ');
insert into TEST_TABLE values (107,'{"ClassId":32000,"Attributes":[{"Name":"ID","Value":"73589"},{"Name":"HREF","Value":"-1"},{"Name":"HPRCSN","Value":"5"}]},{"Name":"HMETHOD","Value":"96"}]} ');
insert into TEST_TABLE values (108,'{"ClassId":32000,"Attributes":[{"Name":"ID","Value":"74015"},{"Name":"HREF","Value":"-1"},{"Name":"HPRCSN","Value":"5"}]},{"Name":"HMETHOD","Value":"96"}]} ');
commit;
Now my actual plan was to get two elements out of these data : HMETH and HPRCSN.
I want to write a sql which will give me the output like this.
But I faced two problem
Each elements position might not same for each row. So i cannot use fixed position for
substr for that.
If the Value of HPRCSN is round then it has "" enclosed and if it is decimal then it comes without "". so all decimal output comes as round integer.
We made some code which is working some of it, but not 100% working because elements position and the decimal values. If anyone have any suggestion to fix this sql it would be so helpful.
select t1.id
,to_number(regexp_substr(replace(regexp_replace(importdata, '[^,[:digit:]]',''),',,',','),'[^,]+',15)) as HMETH
,to_number(regexp_substr(replace(regexp_replace(importdata, '[^,[:digit:]]',''),',,',','),'[^,]+',18)) as HPRCSN
from TEST_TABLE t1;
Here is my output which is wrong for some rows because of the position.

Answer 1

Never use regular expressions to parse HTML JSON; use a proper parser.
You can use JSON_TABLE to extract the name-value pairs:
select id,
classid,
name,
value
from TEST_TABLE t1
CROSS APPLY JSON_TABLE(
t1.importdata,
'$'
COLUMNS (
classid NUMBER PATH '$.ClassId',
NESTED PATH '$.Attributes[*]' COLUMNS (
name VARCHAR2(20) PATH '$.Name',
value VARCHAR2(20) PATH '$.Value'
)
)
);
Which, for your sample data, outputs:
ID
CLASSID
NAME
VALUE
100
30074
TYPE-SPEC
SJ;3;1
100
30074
HREF
-1
100
30074
HMETHOD
96
100
30074
GEO_METHOD
96
100
30074
HPRCSN
2.7676
101
30074
TYPE-SPEC
SJ;3;1
101
30074
HREF
-1
101
30074
HMETHOD
96
101
30074
HPRCSN
3.04
102
30074
TYPE-SPEC
SJ;3;1
102
30074
HREF
-1
102
30074
HMETHOD
96
102
30074
GEO_METHOD
96
102
30074
HPRCSN
77.1814
103
30074
TYPE-SPEC
SJ;3;1
103
30074
HREF
-1
103
30074
HMETHOD
96
103
30074
GEO_METHOD
-1
103
30074
HPRCSN
3.1121
105
32000
ID
69804
105
32000
HREF
-1
105
32000
HPRCSN
5
106
32000
ID
73576
106
32000
HREF
-1
106
32000
HPRCSN
5
107
32000
ID
73589
107
32000
HREF
-1
107
32000
HPRCSN
5
108
32000
ID
74015
108
32000
HREF
-1
108
32000
HPRCSN
5
If you want the values in columns (instead of rows) then use PIVOT:
SELECT *
FROM (
select id,
classid,
name,
value
from TEST_TABLE t1
CROSS APPLY JSON_TABLE(
t1.importdata,
'$'
COLUMNS (
classid NUMBER PATH '$.ClassId',
NESTED PATH '$.Attributes[*]' COLUMNS (
name VARCHAR2(20) PATH '$.Name',
value VARCHAR2(20) PATH '$.Value'
)
)
) j
)
PIVOT (
MAX(value) FOR name IN (
'ID' AS idvalue,
'HREF' AS href,
'GEO_METHOD' AS geomethod,
'HPRCSN' AS hprcsn,
'HMETHOD' AS hmethod
)
);
Which outputs:
ID
CLASSID
IDVALUE
HREF
GEOMETHOD
HPRCSN
HMETHOD
100
30074
null
-1
96
2.7676
96
107
32000
73589
-1
null
5
null
108
32000
74015
-1
null
5
null
101
30074
null
-1
null
3.04
96
106
32000
73576
-1
null
5
null
103
30074
null
-1
-1
3.1121
96
105
32000
69804
-1
null
5
null
102
30074
null
-1
96
77.1814
96
fiddle