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Understanding the GROUP BY and HAVING Clauses in SQL with Examples

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In this tutorial, you will learn about the group by and having clause in SQL. Also, you will learn about the differences that exist between them.

Groupby

The HAVING clause is used in conjunction with the GROUP BY clause to filter groups based on a specified condition. It is used to filter the groups that are returned by the “GROUPBY” clause, and only return the groups that meet the specified condition. The HAVING clause is used to filter the results of the aggregate function and only return the groups that meet a specified condition. For example, you can use the “having” clause to only return groups that have a count of more than a certain number of records.

SELECT COUNT(*) as ‘Number of Orders’,
country FROM orders
GROUP BY country
HAVING COUNT(*) > 50;

In the above example, the query counts the total number of orders for each country while grouping all orders by country. Only nations with more than 50 orders are returned thanks to the HAVING clause’s filtering of the search results.

In conclusion, the HAVING clause is used to filter the groups based on a stated condition, and the GROUP BY clause is used to group rows in a table by one or more columns. These clauses provide robust data analysis and manipulation in SQL when used together.

Having

The HAVING clause is used to filter the results of the aggregate function and only return the groups that meet a specified condition. For example, you can use the HAVING clause to only return groups that have a count of more than a certain number of records, or a sum of a certain value.

SELECT COUNT(*) as ‘Number of Orders’, country
FROM orders
GROUP BY country
HAVING COUNT(*) > 50;

In the above example, the query counts the total number of orders for each country while grouping all orders by country. Only nations with more than 50 orders are returned thanks to the HAVING clause’s filtering of the search results.

It’s important to keep in mind that the HAVING clause, which is applied to the grouped records and used after the GROUP BY clause, can only refer to the columns listed in the GROUP BY clause or to aggregate functions that use these columns.

Difference between Groupby and Having

GROUP BY clause is used to group the data according to a particular column or data.The HAVING clause is used in specific scenarios where more additional conditions along with groupby are required for querying purposes.
 Group by clause cannot contain aggregate functions.Whereas Having a clause can contain aggregate functions such as SUM(), MIN(), MAX(), and AVG().
One can use groupby with a select statement without a clause.When using the aggregate function without the groupby clause, having operates like a where clause.
Groupby groups the output on the basis of some rows or columns.Having restricts the query output by some conditions.

Conclusion

In conclusion, the SQL GROUP BY and HAVING clauses are effective tools for manipulating and analyzing data. Using the GROUP BY clause, you may aggregate data and conduct operations on the gathered data by grouping rows in a table by one or more columns. You can further refine the outcomes of your query by using the HAVING clause in conjunction with the GROUP BY clause to filter groups according to a specified criterion.

Together, these clauses make it simple to arrange, evaluate, and summarize huge data sets, making it simpler to comprehend and draw conclusions from the data. These clauses can be combined with other SQL clauses, including SELECT, WHERE, and ORDER BY, to build strong, complicated queries that can be utilized to address a variety of business concerns.

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