3 Ways to Check Duplicate Record in table Oracle SQL

June 5, 2020Posted inORACLE

How to check duplicate record in table SQL/Oracle?

  • Create table using following script:
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CREATE TABLE TEST_EMP
(
  ENAME   VARCHAR2(10 BYTE),
  DEPTNO  NUMBER(2),
  ID      NUMBER
)
  • Run following script for demo purpose.
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SET DEFINE OFF;
Insert into TEST_EMP (ENAME, DEPTNO, ID)
 Values ('SMITH', 20, 1);
Insert into TEST_EMP (ENAME, DEPTNO, ID)
 Values ('ALLEN', 30, 2);
Insert into TEST_EMP (ENAME, DEPTNO, ID)
 Values ('SMITH', 20, 3);
Insert into TEST_EMP (ENAME, DEPTNO, ID)
 Values   ('VIKAS', 10, 4);
Insert into TEST_EMP   (ENAME, DEPTNO, ID)
 Values   ('VIKAS', 10, 6);
Insert into TEST_EMP   (ENAME, DEPTNO, ID)
 Values   ('ASHISH', 40, 7);
Insert into TEST_EMP   (ENAME, DEPTNO, ID)
 Values   ('SATISH', 50, 8);
Insert into TEST_EMP   (ENAME, DEPTNO, ID)
 Values   ('SATISH', 50, 9);
COMMIT;


Solution 1 :

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SELECT * FROM test_emp
WHERE ID NOT IN 
(SELECT MIN (ID)  FROM test_emp GROUP BY ename);

Or

SELECT * FROM test_emp
WHERE ID NOT IN 
(SELECT max (ID)  FROM test_emp GROUP BY ename);


Solution 2 :

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SELECT * FROM test_emp a
      WHERE ID > (SELECT MIN (ID)
                  FROM test_emp b
                  WHERE a.deptno = b.deptno AND a.ename = b.ename);


Solution 3 :

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SELECT *
  FROM test_emp
 WHERE id IN (SELECT id
                FROM (SELECT id,
                             ROW_NUMBER ()
                                OVER (PARTITION BY ename, deptno ORDER BY id)
                                r
                        FROM test_emp)
               WHERE r > 1);

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