SQLite HAVING Clause

The HAVING clause is used to filter data based on a condition that involves an aggregate function. It is similar to the WHERE clause, but rather than filtering rows based on individual values, it filters groups of rows based on the result of an aggregate function applied to the group.

Syntax

The basic syntax for using the HAVING clause in SQLite is:

SELECT column1, aggregate_function(column2)
FROM table_name
WHERE condition
GROUP BY column1
HAVING condition;

Example

Let's consider an example where we have a table named sales that contains data about the sales transactions of a company. We want to find the total sales for each salesperson and only show the results for salespersons with a total sales value greater than $10,000.

SELECT salesperson, SUM(sales_amount) as total_sales
FROM sales
GROUP BY salesperson
HAVING total_sales > 10000;

Output

The output of the above SQL statement would be a table with two columns: salesperson and total_sales. The total_sales column shows the total sales for each salesperson.

salesperson | total_sales
------------+------------
John        | 15000
Mary        | 12000
Jane        | 11000

Explanation

In the example above, we use the SUM() aggregate function to calculate the total sales for each salesperson in the sales table. We group the data by the salesperson column using the GROUP BY clause.

We use the HAVING clause to filter the groups of salespersons and show only the results for salespersons with a total sales value greater than $10,000.

Use

The HAVING clause is useful when you need to filter data based on aggregate functions, such as finding the highest or lowest values in a group, or filtering out groups that do not meet a certain criteria. It can be used with functions like SUM, AVG, MIN, MAX, and COUNT.

Important Points

• The HAVING clause is only used with GROUP BY clauses.
• Aggregate functions are used with the HAVING clause to filter the results.
• The HAVING clause can only be used to filter based on the results of aggregate functions.
• The HAVING clause can be used with multiple conditions using AND or OR operators.
• The HAVING clause is evaluated after the GROUP BY clause.

Summary

In this tutorial, we learned about the HAVING clause in SQLite and how it can be used to filter data based on aggregate functions. We saw an example of using the HAVING clause to find the total sales for each salesperson and filter out salespersons with a total sales value less than $10,000. The HAVING clause is an important tool for working with aggregate data and can help you gain insights into your data that would be difficult to obtain otherwise.