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How do I remove duplicates in a PL SQL query?

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Best Practices for Removing Duplicates in PL/SQL Queries Introduction: As a seasoned PL/SQL tutor registered on UrbanPro.com, I understand the importance of efficiently handling data duplicates in PL/SQL queries. Removing duplicates is a common requirement in database management, and there are several...
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Best Practices for Removing Duplicates in PL/SQL Queries

Introduction: As a seasoned PL/SQL tutor registered on UrbanPro.com, I understand the importance of efficiently handling data duplicates in PL/SQL queries. Removing duplicates is a common requirement in database management, and there are several strategies to achieve this in PL/SQL.

Methods for Removing Duplicates:

  1. Using DISTINCT Keyword:

    • The simplest way to remove duplicates is by using the DISTINCT keyword in your SELECT statement.
    • Example:
      sql

 

    • SELECT DISTINCT column1, column2 FROM your_table;
    • This method works well when you want distinct combinations of values in specific columns.
  • Aggregate Functions:

    • Utilize aggregate functions like MIN or MAX along with the GROUP BY clause.
    • Example:
      sql
    • SELECT column1, MAX(column2) FROM your_table GROUP BY column1;
    • This approach is suitable when you need to retain specific columns and aggregate others.
  • ROWID or ROWNUM:

    • Leverage the ROWID or ROWNUM pseudo-columns to uniquely identify rows.
    • Example:
      sql

 

    • SELECT * FROM ( SELECT column1, column2, ROW_NUMBER() OVER (PARTITION BY column1 ORDER BY column2) as rnum FROM your_table ) WHERE rnum = 1;
    • This method is effective when you want to keep a single row for each unique combination.

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For in-depth understanding and hands-on experience in PL/SQL, consider enrolling in specialized training courses. UrbanPro.com offers some of the best online coaching for PL/SQL training, providing a structured learning environment with experienced tutors.

  • PL/SQL Training Overview:

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Conclusion: Removing duplicates in a PL/SQL query involves selecting distinct values using the DISTINCT keyword, leveraging aggregate functions with the GROUP BY clause, or utilizing pseudo-columns like ROWID or ROWNUM. For a more comprehensive understanding and practical application, consider enrolling in the best online coaching for PL/SQL training available on UrbanPro.com.

 
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Related Questions

I need your help to choose my career as I have three years of gap between my education. I know SQL. Can anyone tell me should I choose MS SQL server or oracle because I am interested in the database? Which one will be better to learn to get into the IT industry? Please help me! Thank you!
As you are strong and interested in SQL, why not to choose ETL Testing? It has a good career ahead in data projects. To survive in the market, you need both Oracle & SQL Server. Actually, both are almost same but are different products.
Santhosh

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