Question

Hi am new to Teradata and am stuck with a problem

There is an ID table which stores an Unique ID given to each person

CREATE TABLE IDS(
ID VARCHAR(8),
UPDATED_DATE DATE)

Then we have a name and address table which do not have any primary keys that stores demographic information for the IDS

CREATE TABLE NAMES(
ID VARCHAR(8),
NAME VARCHAR(50))
CREATE TABLE ADRRESSES(
ID VARCHAR(8)
ADDRESS VARCHAR(200))

Now each ID can have multiple name and IDS. However for names and address I want to use the ones that are have more counts. If two names have the same COUNT I just want the First row

ID NAME COUNT

1234 John Smith 6

1234 Johnnie Smith 6

1234 J Smith 2

In the above example I want the name John Smith. Here is the left Join I am performing since an ID may not have a name or address. Here is what I am trying

SELECT * FROM
(SELECT ID as V_ID from IDS) a
LEFT JOIN
(SELECT ID, NAME, COUNT(*) AS COUNTER,(RANK() OVER(ORDER BY COUNTER DESC)) AS RNK
FROM NAMES 
GROUP BY ID)b
ON a.ID = b.ID
AND b.RNK = 1            -- Should give me only the first row
LEFT JOIN
(SELECT ID, ADDRESS, COUNT(*) AS COUNTER, (RANK() OVER (ORDER BY COUNTER DESC) ) AS RNK
FROM ADDRESSES
GROUP BY ID) c
ON c.ID = a.ID
And c.RNK = 1

However this is not getting me the desired result. I tried using ROW NUMBER instead of RANK also but still no results. How should I write this query in TERDATA?

Answer 1

I solved it …I needed a qualify and a partition by

SELECT * FROM
    (SELECT ID as V_ID from IDS) a
    LEFT JOIN
    (SELECT ID, NAME, COUNT(*) AS COUNTER
    FROM NAMES
    GROUP BY ID
    qualify ROW_NUMBER() OVER(PARTITION BY ID ORDER BY COUNTER DESC) = 1
    )b
    ON a.ID = b.ID
    LEFT JOIN
    (SELECT ID, ADDRESS, COUNT(*) AS COUNTER
    FROM ADDRESSES
    GROUP BY ID
    qualify ROW_NUMBER() OVER(PARTITION BY ID ORDER BY COUNTER DESC) = 1
    ) c
    ON c.ID = a.ID