Retrieving data from JSON column in SQL table

Question

I wonder how to retrieve data from json column in SQL. regexp_substr may work or that one as its in Vertica table. I'm quite newbie and would be very grateful for any help which can help me to understand how to for example:

• find prem_amount for specific OFFICE_ID

Should I divide whole structure below on smaller pieces like here to understand structure?

[{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["1"],"intervals":[{"end_offset":464400,"start_at":null,"start_offset":457200,"end_at":null}],"id":"1","OFFICE_ID":"1","content_hash_id":"1","inc_params":{"is_commissionable":false,"prem_amount":25.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["2"],"intervals":[{"end_offset":550800,"start_at":null,"start_offset":543600,"end_at":null}],"id":"2","OFFICE_ID":"2","content_hash_id":"2","inc_params":{"is_commissionable":false,"prem_amount":25.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1.5"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["3"],"intervals":[{"end_offset":471600,"start_at":null,"start_offset":464400,"end_at":null}],"id":"3","OFFICE_ID":"3","content_hash_id":"3","inc_params":{"is_commissionable":false,"prem_amount":25.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1.5"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["4"],"intervals":[{"end_offset":558000,"start_at":null,"start_offset":550800,"end_at":null}],"id":"4","OFFICE_ID":"4","content_hash_id":"4","inc_params":{"is_commissionable":false,"prem_amount":25.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["5"],"intervals":[{"end_offset":478800,"start_at":null,"start_offset":471600,"end_at":null}],"id":"5","OFFICE_ID":"5","content_hash_id":"5","inc_params":{"is_commissionable":false,"prem_amount":20.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["6"],"intervals":[{"end_offset":565200,"start_at":null,"start_offset":558000,"end_at":null}],"id":"6","OFFICE_ID":"6","content_hash_id":"6","inc_params":{"is_commissionable":false,"prem_amount":20.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1.5"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["7"],"intervals":[{"end_offset":486000,"start_at":null,"start_offset":478800,"end_at":null}],"id":"7","OFFICE_ID":"7","content_hash_id":"7","inc_params":{"is_commissionable":false,"prem_amount":25.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1.5"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["8"],"intervals":[{"end_offset":572400,"start_at":null,"start_offset":565200,"end_at":null}],"id":"8","OFFICE_ID":"8","content_hash_id":"8","inc_params":{"is_commissionable":false,"prem_amount":25.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1.5"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["9"],"intervals":[{"end_offset":493200,"start_at":null,"start_offset":486000,"end_at":null}],"id":"9","OFFICE_ID":"9","content_hash_id":"9","inc_params":{"is_commissionable":false,"prem_amount":25.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1.5"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["10"],"intervals":[{"end_offset":579600,"start_at":null,"start_offset":572400,"end_at":null}],"id":"10","OFFICE_ID":"10","content_hash_id":"10","inc_params":{"is_commissionable":false,"prem_amount":25.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["11"],"intervals":[{"end_offset":500400,"start_at":null,"start_offset":493200,"end_at":null}],"id":"11","OFFICE_ID":"11","content_hash_id":"11","inc_params":{"is_commissionable":false,"prem_amount":20.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}},{"Constraint_a":{"match_all":false,"children":[{"match_all":true,"constraints":[{"operator":"GREATER_OR_EQUAL","property":"RATE","value":"0.850"},{"operator":"GREATER_OR_EQUAL","property":"CALLS_PER_HOUR","value":"1"},{"operator":"GREATER_OR_EQUAL","property":"IN_RATE","value":"1.000"}]}],"constraints":[]},"constraint_ids":["12"],"intervals":[{"end_offset":586800,"start_at":null,"start_offset":579600,"end_at":null}],"id":"12","OFFICE_ID":"12","content_hash_id":"12","inc_params":{"is_commissionable":false,"prem_amount":20.0,"fee":0.1},"filters":[],"visible_office_name":"site_trix","legacy_params":{}}]

Thank you for help!

Answer 1

How did you get the JSON data into Vertica? Are you putting it into a VARCHAR? That's not ideal because you can't easily validate it (as demonstrated by this answer) or extract values from it. Instead, you can load JSON data using the FJSONParser. For example:

vsql> create table super(age int, name varchar);

vsql> copy super from stdin parser fjsonparser();
Enter data to be copied followed by a newline.
End with a backslash and a period on a line by itself.
>> {"age": 5, "name": "Tim"}
>>  {"age": 3}
>>  {"name": "Fred"}
>>  {"name": "Bob", "age": 10}
>> \.

vsql> select * from super;
 age | name
-----+------
     | Fred
  10 | Bob
   5 | Tim
   3 |
(4 rows)

Obviously you won't be typing your JSON on STDIN; that's just the example in the documentation. You can load from a JSON file like this:

vsql> COPY SE.PostLinks FROM '"$loaddir"/PostLinks.json' PARSER fjsonparser();

(Guess what data I was experimenting with. :-) )

Answer 2

The json you provided here is malformed. You can quickly check by using an online json validator. There are several websites out there you can use. For example: JSON Formatter

More information on querying json data can be found here: JSON data in SQL Server