How to execute multiple case when statements for each iteration in SAS? - sql

Question

I'm using proc sql, and using multiple case when statements to add columns with either a 0 or 1 if the condition is met. It's a big bottleneck right now since it has to scan through each id for each case when statement. So I'm trying to figure out a way to somehow nest the case statements to perform each iteration, instead of having to iterate for all case statements.
This is an example of my code that is taking too long right now.
SELECT *,
CASE WHEN loannumber IN (
SELECT loannumber FROM PREPAY_LOAN_IDS
) THEN 1
ELSE 0 END AS PREPAY_FLAG,
CASE WHEN loannumber IN (
SELECT loannumber FROM DPD_30_IDS
) THEN 1
ELSE 0 END AS DPD_30_FLAG,
CASE WHEN loannumber IN (
SELECT loannumber FROM DPD_60_IDS
) THEN 1
ELSE 0 END AS DPD_60_FLAG,
CASE WHEN loannumber IN (
SELECT loannumber FROM DPD_90_IDS
) THEN 1
ELSE 0 END AS DPD_90_FLAG,
CASE WHEN loannumber IN (
SELECT loannumber FROM DPD_120_IDS
) THEN 1
ELSE 0 END AS DPD_120_FLAG,
CASE WHEN loannumber IN (
SELECT loannumber FROM FORECLOSURE_IDS
) THEN 1
ELSE 0 END AS FORECLOSURE_FLAG
FROM(
SELECT *
FROM MORTGAGES
)

Answer 1

The below query will work faster than the one you have posted as the input table is not completely access to retrieve the results. Try running this query and see how it performs.
SELECT M.*,
CASE WHEN PLI.loannumber IS NOT NULL THEN 1
ELSE 0 END AS PREPAY_FLAG,
CASE WHEN D3I.loannumber IS NOT NULL THEN 1
ELSE 0 END AS DPD_30_FLAG,
CASE WHEN D6I.loannumber IS NOT NULL THEN 1
ELSE 0 END AS DPD_60_FLAG,
CASE WHEN D9I.loannumber IS NOT NULL THEN 1
ELSE 0 END AS DPD_90_FLAG,
CASE WHEN D12I.loannumber IS NOT NULL THEN 1
ELSE 0 END AS DPD_120_FLAG,
CASE WHEN FCI.loannumber IS NOT NULL THEN 1
ELSE 0 END AS FORECLOSURE_FLAG
FROM MORTGAGES M
LEFT JOIN
PREPAY_LOAN_IDS PLI
ON M.loannumber = PLI.loannumber
LEFT JOIN
DPD_30_IDS D3I
ON M.loannumber = D3I.loannumber
LEFT JOIN
DPD_30_IDS D6I
ON M.loannumber = D6I.loannumber
LEFT JOIN
DPD_90_IDS D9I
ON M.loannumber = D9I.loannumber
LEFT JOIN
DPD_90_IDS D12I
ON M.loannumber = D12I.loannumber
LEFT JOIN
FORECLOSURE_IDS FCI
ON M.loannumber = FCI.loannumber
;

Answer 2

Since you're using SAS, here's a data step alternative, assuming that each of your datasets is already either sorted by or has an index on loannumber:
data want;
merge MORTGAGES(in = Mortgages)
PREPAY_LOAN_IDS(in = PLIDs keep = loannumber)
/*etc*/
;
by loannumber;
if Mortgages;
PREPAY_FLAG = PLIDs;
/*etc*/
run;
N.B. You will get duplicated records from MORTGAGES if you have duplicates in any of your other tables.