Is there a way to Pivot Oracle SQL results to show 1 unique ID and the non null values in each column? - sql

Question

I am an Oracle SQL beginner and I have an issue with the code below:
SELECT unique_id,
CASE
WHEN type LIKE 'E-%' THEN
'electric'
ELSE
null
END electric_flag,
CASE
WHEN type LIKE 'G-%' THEN
'gas'
ELSE
null
END gas_flag,
CASE
WHEN type LIKE 'W-%' THEN
'water'
ELSE
null
END water_flag,
CASE
WHEN type LIKE 'S-%' THEN
'wastewater'
ELSE
null
END wastewater_flag
FROM (SELECT unique_id, type, end_dt
FROM table
WHERE end_dt IS NULL)
Which gives me the following results:
My goal is to have the results show like this:
It's almost like I want to group the results by the id, ignore rows that are all null, but combine the rows that return with the flag into a single row.
Any help would be greatly appreciated!

Answer 1

Here's a pseudo-code:
SELECT
*
FROM
(
SELECT
unique_id,
CASE type WHEN LIKE 'E-%' THEN 'electric'
WHEN LIKE 'G-%' THEN 'gas'
WHEN LIKE 'W-%' THEN 'water'
WHEN LIKE 'S-%' THEN 'wastewater'
ELSE NULL
END flag
FROM {table}
WHERE end_dt IS NULL
)
PIVOT
(
MAX(flag)
FOR flag IN ('electric' electric_flag, 'gas' gas_flag, 'water' water_flag, 'wastewater' wastewater_flag)
)
Here's an Oracle SQL Fiddle

Answer 2

You're almost there;
Conditionals are needed but they should be aggregated
a Grouping By unique_id clause should be added during the aggregation
a subquery is not needed
using ELSE null cases are redundant
it's suitable to add a ROW_NUMBER() analytic function in order to generate a column with ordinal values
So, use the following SQL Select Statement of Conditional Aggregation :
SELECT ROW_NUMBER() OVER (ORDER BY unique_id) AS id,
MAX(CASE
WHEN type LIKE 'E-%' THEN
'electric'
END) AS electric_flag,
MAX(CASE
WHEN type LIKE 'G-%' THEN
'gas'
END) AS gas_flag,
MAX(CASE
WHEN type LIKE 'W-%' THEN
'water'
END) AS water_flag,
MAX(CASE
WHEN type LIKE 'S-%' THEN
'wastewater'
END) AS wastewater_flag
FROM t
WHERE end_dt IS NULL
GROUP BY unique_id
Demo