I have a column in my table having values of format:
COURSE_214/MODULE_5825/SUBMODULE_123/..../GOAL_124/ACTIVITY_125.
I need value for goal i.e 124 from goal_124. I am planning to use 'regexp_split_to_array' but don't know how to use elements from array.
I am using postgres 9.2.
You can use split_part like so:
select split_part(split_part('COURSE_214/MODULE_5825/SUBMODULE_123/..../GOAL_124/ACTIVITY_125', '/GOAL_', 2), '/', 1)
i.e.
select split_part(split_part(fieldname, '/GOAL_', 2), '/', 1)
Result:
124
Using json_object():
select json_object(string_to_array(translate(params, '_', '/'), '/'))
from test
json_object
------------------------------------------------------------------------------------------------
{"COURSE" : "214", "MODULE" : "5825", "SUBMODULE" : "123", "GOAL" : "124", "ACTIVITY" : "125"}
(1 row)
select json_object(string_to_array(translate(params, '_', '/'), '/'))->>'GOAL' as goal
from test
goal
------
124
(1 row)
The column has a format suitable for json. I would suggest to change the type of the column to jsonb. The first query may be used as a converter.
After the conversion you would access the parameters in an easy way, e.g.:
select *
from test
where params->>'COURSE' = '214'
and (params->>'GOAL')::int > 120;
Simple select of all GOAL_ parameters (if there are more than one)
select ltrim(elem, 'GOAL_')
from (
select unnest(string_to_array(params, '/')) elem
from test
) sub
where elem like 'GOAL_%'
json_object() you need Postgres 9.3+ (for the jsonb type - 9.4+).hstore. However my solution assumes unique keys. Perhaps it would be worthwhile to ask a new question with the detailed description of the parameters structure (Postgres version should be always included in a question).You may try using regular expressions, getting the string between slashes
select substring(your_column from '^.*/(.*)/.*$') from your_table
If you expect to find in that part the GOAL value, use
select substring(your_column from '/GOAL_(.*)/') from your_table