What is the DISTINCT Clause?

What is the DISTINCT Clause?

The DISTINCT clause is used to retrieve unique values from a specific column or combination of columns in a result set. It eliminates duplicate rows and ensures that only distinct values are returned. DISTINCT can improve query performance by reducing the amount of data that needs to be processed and returned. This can lead to faster query execution times, especially when dealing with large datasets....

What is GROUP BY Clause?

The GROUP BY clause is used in conjunction with aggregate functions like SUM, AVG, COUNT, MIN, and MAX to group the result set by one or more columns. It is used to divide the rows returned from the SELECT statement into groups based on the specified columns....

Examples of DISTINCT and GROUP BY Clause

To understand DISTINCT and GROUP BY Clause in PL/SQL we need a table on which we will perform various operations and queries. Here we will consider a table called employees which contains employee_id, employee_name, salary, age and department_name as Columns....

Difference Between DISTINCT and GROUP BY

The Differnce between “DISTINCT” and “GROUP BY” is as follows:...

Conclusion

Overall, understanding the differences between DISTINCT and GROUP BY clauses in PL/SQL is crucial for efficient data manipulation. DISTINCT is used to retrieve unique values from columns, eliminating duplicates and ensuring each value appears only once. On the other hand, GROUP BY is used to group rows based on specified columns, allowing for the application of aggregate functions to calculate summary information for each group. While DISTINCT is suitable for obtaining unique values, GROUP BY is essential for performing complex analyses and summarizing data based on certain criteria....