Difference Between DISTINCT and GROUP BY
The Differnce between “DISTINCT” and “GROUP BY” is as follows:
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DISTINCT |
GROUP BY |
|---|---|
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Retrieve unique values from one or more columns in the result set. |
Group rows based on specified columns in the result set. |
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Eliminates duplicate rows from the result set, ensuring each value appears only once. |
Allows for the application of aggregate functions like SUM(), AVG(), COUNT(), etc., to calculate summary information for each group. |
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Operates on individual columns or combinations of columns specified in the SELECT statement. |
Rows with identical values in the specified columns are grouped together. |
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Has a simple syntax and is easy to use in SQL queries. |
GROUP BY can operate on multiple columns and allows for complex grouping criteria. |
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Results in a single column or multiple columns with unique values. |
Results in multiple groups, each with its own summary information based on the aggregated data. |
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Does not perform any calculations or aggregations on the data that focuses on uniqueness. |
Can be combined with conditional expressions or CASE statements for more complex aggregations. |
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Often used to filter out duplicate records when querying databases. |
Suitable for summarizing data based on certain criteria, such as department-wise sales totals or average test scores per student. |
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Generally faster for small result sets as it only needs to eliminate duplicates without any calculations. |
May be slower, especially with large data sets, due to the grouping and potential aggregations involved. |
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Ideal for obtaining a list of unique values from specific columns, such as unique product names or customer IDs. |
Essential for performing complex analyses, such as identifying trends or patterns within data sets. |
Difference Between Distinct and Group By in PL/SQL
In PL/SQL, knowing the difference between DISTINCT and GROUP BY is important for working with data effectively. Although DISTINCT and GROUP BY might seem similar, they serve different purposes. In this article, we’ll explore DISTINCT and GROUP BY Clause with the syntax and various examples along the difference between them for better understanding.