The SQL HAVING clause is used in conjunction with the GROUP BY clause to filter the results of a query based on the group by clause. The HAVING clause is used to filter the results of a GROUP BY clause, whereas the WHERE clause is used to filter the results of a query before the GROUP BY clause is applied.

For example, consider a table called sales that has the following columns: customer_id, product_id, and sales_amount.

If we want to find the total sales amount for each customer, we can use the following query:

SELECT customer_id, SUM(sales_amount) as total_sales

FROM sales

GROUP BY customer_id;

This query will return a list of customers and their total sales amount.

However, if we only want to see customers who have made more than $1000 in sales, we can add a HAVING clause to the query like this:

SELECT customer_id, SUM(sales_amount) as total_sales

FROM sales

GROUP BY customer_id

HAVING total_sales > 1000;

This will return only those customers who have made more than $1000 in sales.

The HAVING clause is commonly used in combination with GROUP BY and aggregate functions like SUM, AVG, COUNT, etc. to filter the results of a query based on the grouped data. It provides a way to apply additional criteria to the groups that are generated by the GROUP BY clause.

The HAVING clause is an optional clause in SQL that can be used in combination with the GROUP BY clause to filter the results of a query based on the groups that are generated by the GROUP BY clause. It allows you to apply additional criteria to the groups generated by the GROUP BY clause, and is useful for filtering the results of a query based on the grouped data.

Want to learn more about aggregate functions and having clause in SQL Server?

https://stevestedman.com/aggregation

 

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