Parsing within a field using SQL - sql

Question

We are receiving data in one column where further parsing is needed. In this example the separator is ~.
Goal is to grab the pass or fail value from its respective pair.
SL
Data
1
"PARAM-0040,PASS~PARAM-0045,PASS~PARAM-0070,PASS"
2
"PARAM-0040,FAIL~PARAM-0045,FAIL~PARAM-0070,PASS"
Required outcome:
SL
PARAM-0040
PARAM-0045
PARAM-0070
1
PASS
PASS
PASS
2
FAIL
FAIL
PASS
This will be a part of a bigger SQL query where we are selecting many other columns, and these three columns are to be picked up from the source as well and passed in the query as selected columns.
E.g.
Select Column1, Column2, [ Parse code ] as PARAM-0040, [ Parse code ] as PARAM-0045, [ Parse code ] as PARAM-0070, Column6 .....
Thanks

Answer 1

You can do that with a regular expression. But regexps are non-standard.
This is how it is done in postgresql: REGEXP_MATCHES()
https://www.postgresqltutorial.com/postgresql-regexp_matches/
In postgresql regexp_matches returns zero or more values. So then it has to be broken down (thus the {})
A simpler way, also in postgresql is to use substring.
substring('foobar' from 'o(.)b')
Like:
select substring('PARAM-0040,PASS~PARAM-0045,PASS~PARAM-0070,PASS' from 'PARAM-0040,([^~]+)~');
substring
-----------
PASS
(1 row)

Answer 2

You may use the str_to_map function to split your data and subsequently extract each param's value. This example will first split each param/value pair by ~ before splitting the parameter and value by ,.
Reproducible example with your sample data:
WITH my_table AS (
SELECT 1 as SL, "PARAM-0040,PASS~PARAM-0045,PASS~PARAM-0070,PASS" as DATA
UNION ALL
SELECT 2 as SL, "PARAM-0040,FAIL~PARAM-0045,FAIL~PARAM-0070,PASS" as DATA
),
param_mapped_data AS (
SELECT SL, str_to_map(DATA,"~",",") param_map FROM my_table
)
SELECT
SL,
param_map['PARAM-0040'] AS PARAM0040,
param_map['PARAM-0045'] AS PARAM0045,
param_map['PARAM-0070'] AS PARAM0070
FROM
param_mapped_data
Actual code assuming your table is named my_table
WITH param_mapped_data AS (
SELECT SL, str_to_map(DATA,"~",",") param_map FROM my_table
)
SELECT
SL,
param_map['PARAM-0040'] AS PARAM0040,
param_map['PARAM-0045'] AS PARAM0045,
param_map['PARAM-0070'] AS PARAM0070
FROM
param_mapped_data
Outputs:
sl
param0040
param0045
param0070
1
PASS
PASS
PASS
2
FAIL
FAIL
PASS