ROWID TO FIND DUPLICATES

  1. What is ROWID?
    • ROWID is a pseudo column in some database systems, uniquely identifying a row within a table.
  2. Uniqueness:
    • Each ROWID is unique for every row in a table, providing a distinct identifier.
  3. Physical Address:
    • ROWID often represents the physical storage location of a row, including details like data block, file, and slot.
  4. Usage Considerations:
    • While useful for certain low-level operations, ROWID is not recommended for general application use.
  5. MIN(ROWID) for Deduplication:
    • MIN(ROWID) can be used to identify and delete duplicate rows based on a specific column, ensuring only one row per unique value is retained.
  6. Database Dependency:
    • The behavior and usage of ROWID may vary between different database systems, and it’s not a portable feature across all SQL databases.
  7. Preferred Alternatives:
    • For user-friendly and portable applications, it’s often better to rely on primary keys or unique constraints instead of ROWID.

 

USING ROWID TO FIND DUPLICATE VALUES

— ROWID MAY BE USEFUL IN CERTIAN INSTANCES AS EVERY ROW IN SQL IS UNIQUE, SO WHEN A TABLE DOES NOT HAVE

— UNIQUE CONSTRAINTS, ONE WAY TO FIND DUPLICATE IS TO USE MIN(ROWID). THIS WILL REUTURN UNIQUE INSTANCES

— OP THAT VARIABLE

 

–FOR EXAMPLE

 

CATEGORY_NAME

DELETE FROM PTBL_CATEGORY
WHERE ROWID NOT IN(
SELECT MIN(ROWID)
FROM PTBL_CATEGORY
GROUP BY CATEGORY_NAME
);

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