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Finding Duplicate records and Deleting Duplicate records in TERADATA

By Anonymous
Requirement:
Finding duplicates and removing duplicate records by retaining original record in TERADATA

Suppose I am working in an office and My boss told me to enter the details of a person who entered in to office. I have below table structure.
Create Table DUP_EXAMPLE
(
PERSON_NAME VARCHAR2(50),
PERSON_AGE INTEGER,
ADDRS VARCHAR2(150),
PURPOSE VARCHAR2(250),
ENTERED_DATE DATE
)

If a person enters more than once then I have to insert his details more than once.
First time, I inserted below records.

INSERT INTO DUP_EXAMPLE VALUES('Krishna reddy','25','BANGALORE','GENERAL',TO_DATE('01-JAN-2014','DD-MON-YYYY'))
INSERT INTO DUP_EXAMPLE VALUES('Anirudh Allika','25','HYDERABAD','GENERAL',TO_DATE('01-JAN-2014','DD-MON-YYYY'))
INSERT INTO DUP_EXAMPLE VALUES('Ashok Vunnam','25','CHENNAI','INTERVIEW',TO_DATE('01-JAN-2014','DD-MON-YYYY'))

And on same day the person named Ashok came again to office and I entered once again into table.
INSERT INTO DUP_EXAMPLE VALUES ('Ashok Vunnam','25','CHENNAI','INTERVIEW',TO_DATE('01-JAN-2014','DD-MON-YYYY'))

Now, I have below data in the table.
SELECT * FROM DUP_EXAMPLE

PERSON_NAME
PERSON_AGE
ADDRS
PURPOSE
ENTERED_DATE
Krishna reddy
25
BANGALORE
GENERAL
01-JAN-2014
Anirudh Allika
25
HYDERABAD
GENERAL
01-JAN-2014
Ashok Vunnam
25
CHENNAI
INTERVIEW
01-JAN-2014
Ashok Vunnam
25
CHENNAI
INTERVIEW
01-JAN-2014


I have a requirement to get the person details that who entered more than once in a day. So, now I have to run below query to get correct result set.
We can write this query in two ways.
1) First Option:

SELECT
PERSON_NAME,
PERSON_AGE,
ADDRS,
PURPOSE,
ENTERED_DATE,
COUNT(*)
FROM DUP_EXAMPLE
GROUP BY 1,2,3,4,5
HAVING COUNT(*)>1

2) Second Option:

SELECT
PERSON_NAME,
PERSON_AGE,
ADDRS,
PURPOSE,
ENTERED_DATE,
ROW_NUMBER() OVER(PARTITION BY PERSON_NAME,PERSON_AGE,ADDRS,PURPOSE,ENTERED_DATE ORDER BY PERSON_NAME,PERSON_AGE,ADDRS,PURPOSE,ENTERED_DATE) AS RECORD_NUMBER
FROM DUP_EXAMPLE
WHERE RECORD_NUMBER > 1

And we can delete duplicate records by retaining original record using below query.

DELETE FROM DUP_EXAMPLE
WHERE ROW_NUMBER() OVER(PARTITION BY PERSON_NAME,PERSON_AGE,ADDRS,PURPOSE,ENTERED_DATE ORDER BY PERSON_NAME,PERSON_AGE,ADDRS,PURPOSE,ENTERED_DATE) > 1

Note: Wherever you go for interview, you will face this question How to find duplicates and how to delete duplicate records by retaining original record.

Comments

  1. UnknownJuly 12, 2017 at 2:29 PM

    Ordered analytical functions are not allowed in WHERE Clause anymore in teradata

    ReplyDelete
  2. UnknownNovember 7, 2017 at 1:51 AM

    This comment has been removed by the author.

    ReplyDelete

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