GROUP BY Vs DISTINCT in PostgreSQL
The Difference between “DISTINCT” and “GROUP BY” in PostgreSQL:
Feature |
DISTINCT |
GROUP BY |
---|---|---|
Syntax |
SELECT DISTINCT column1, column2 FROM table_name; |
SELECT column1, aggregate_function(column2) FROM table_name GROUP BY column1; |
Used For |
To get Unique values from a single column |
To get Grouped data (by one or more columns) with aggregate function calculation. |
Columns in SELECT |
One Column for which we want the unique values |
Columns mentioned in Group By Clause and the columns on which aggregate functions are applied. |
Speed |
Faster Comparison to Group By |
Slower than Distinct in large data sets due to aggregation |
Example usage |
To get the unique name of products or customer ID |
Used for identifying patterns in a dataset |
Group By Vs Distinct in PostgreSQL
The GROUP BY and DISTINCT clauses are essential in PostgreSQL for efficient data operations. The DISTINCT clause is used to retrieve unique values from a designated column or combination of columns within a result set, while the GROUP BY clause is used with aggregate functions to organize the result set based on one or more columns.
Distinct is good for retrieving unique values from a column, while GROUP BY is used to summarize the data. The GROUP BY clause is slower than the DISTINCT clause in large data sets due to aggregation. Understanding the differences between these two clauses is crucial for identifying patterns in datasets and optimizing database performance.