Oracle Pivot/Decode - sql

Question

Sample Table
EmployeeID | AssignmentID | WageCode | CompanyName | BillRate | BillTotal
1 | 1 | Regular | CompanyOne | 10 | 400
1 | 2 | Regular | CompanyTwo | 11 | 440
1 | 1 | Overtime | CompanyOne | 15 | 150
1 | 1 | Mileage | CompanyOne | 0 | 20
2 | 3 | Regular | CompanyThree| 20 | 800
2 | 3 | Regular | CompanyThree| 20 | 800
2 | 3 | Overtime | CompanyThree| 30 | 90
2 | 3 | Mileage | CompanyThree| 0 | 60
I want to only show rows with a WageCode of 'Regular', grouped by EmployeeID, WageCode, AssignmentID, CompanyName and BillRate, and pivot the other wage codes into columns.
The final result should look like this:
EmployeeID | AssignmentID | CompanyName | RegBillRate | RegBill | OTBillRate | OTBill | MileageBill
1 | 1 | CompanyOne | 10 | 400 | 15 | 150 | 20
1 | 2 | CompanyTwo | 11 | 440 | 0 | 0 | 0
2 | 3 | CompanyThree| 20 | 1600 | 30 | 90 | 60
What's a cleaner way to do this that's not a bunch of with statements like this:
with regular as
(select EmployeeID, AssignmentID, CompanyName, BillRate, sum(BillTotal) Total from SampleTable where wage code = 'Regular' group by EmployeeID, AssignmentID, CompanyName, BillRate
),
overtime as
(select EmployeeID, AssignmentID, CompanyName, BillRate, sum(BillTotal) Total from SampleTable where wage code = 'Overtime' group by EmployeeID, AssignmentID, CompanyName, BillRate
),
mileage as
(select EmployeeID, AssignmentID, CompanyName, BillRate, sum(BillTotal) Total from SampleTable where wage code = 'Mileage' group by EmployeeID, AssignmentID, CompanyName, BillRate
)
select r.*, o.BillRate, o.Total, m.Total
from regular r
left outer join overtime o
on r.EmployeeID = o.EmployeeID and r.AssignmentID= o.AssignmentID and r.CompanyName= o.CompanyName and r.BillRate= o.BillRateand
left outer join mileage m
on r.EmployeeID = m.EmployeeID and r.AssignmentID= m.AssignmentID and r.CompanyName= m.CompanyName and r.BillRate= m.BillRateand
The query above is paraphrased and probably doesn't work.
What's a better way to do this with some combination of decode and pivot? Is a single pivot table possible?

Answer 1

PIVOT: The Oracle PIVOT clause allows you to write a cross-tabulation query starting in Oracle 11g. This means that you can aggregate your results and rotate rows into columns.
DECODE: The Oracle/PLSQL DECODE function has the functionality of an IF-THEN-ELSE statement.
For your use case, you can use pivot and decode in the following way:
SELECT
EmployeeID, AssignmentID, CompanyName,
decode(REG_BILLRATE, NULL, 0, REG_BILLRATE) AS REG_BILLRATE,
decode(REG_FILL, NULL, 0, REG_FILL) AS REG_FILL,
decode(OT_BILLRATE, NULL, 0, OT_BILLRATE) AS OT_BILLRATE,
decode(OT_FILL, NULL, 0, OT_FILL) AS OT_FILL,
decode(MILEAGE_FILL, NULL, 0, MILEAGE_FILL) AS MILEAGE_FILL
FROM nbitra.tmp
pivot
(
max(BillRate) AS BillRate, sum(BillTotal) AS Fill
for WageCode IN ('Regular' Reg , 'Overtime' OT , 'Mileage' Mileage )
);
Note: The code replaces nulls with 0.

Answer 2

I think you just want conditional aggregation:
select EmployeeID, AssignmentID, CompanyName,
sum(case when WageCode = 'Regular' then billrate end) as regular_billrate,
sum(case when WageCode = 'Regular' then BillTotal end) as regular_billtotal,
sum(case when WageCode = 'Overtime' then billrate end) as ot_billrate,
sum(case when WageCode = 'Overtime' then BillTotal end) as ot_billtotal,
sum(case when WageCode = 'Mileage' then billrate end) as mileage_billrate,
sum(case when WageCode = 'Mileage' then BillTotal end) as mileage_billtotal
from SampleTable st
group by EmployeeID, AssignmentID, CompanyName;