![]() However, I want my code to include them in this result table and I want to see explicitly that they’ve made zero appointments. I can conclude that the two buyers missing are those who have had zero service appointments up until now. However, scroll up a little and you’ll see there are five records in the table car_buyers. The result shows three buyers with a number of appointments. ![]() To count the number of appointments, I’ve used the COUNT() function on the column id from the table service_appointment.ĭo you want to see what result this code returns? I’m sure you do. What did I do here? I’ve included id, first_name, and last_name from the table car_buyers in the SELECT list and in GROUP BY. GROUP BY cb.id, cb.first_name, cb.last_name Intuitively, I might write this code in an attempt to solve the problem: If I do that, it means I’ve succeeded in including zero (0) in the COUNT() aggregate. Those with zero appointments could be buyers that just bought a new car, so there hasn’t been enough time to need a service appointment. I also want that list to include those car buyers who haven’t had a service appointment yet, and I want to see a zero by their names. Using these tables, I want to get a list of my car buyers along with the number of service appointments they had up until now. The service_appointmenttable contains this data on various car service appointments: id It’s a simple list of car buyers for a fictional car sale and repair shop. The table car_buyers contains this data: id There are two tables I’ll use for my example: car_buyers and service_appointment. First, you should understand how aggregate functions work if you’re not familiar with them, check out our Beginner’s Guide to SQL Aggregate Functions and Overview of SQL Aggregate Functions before continuing. How do you achieve that?ĭoes this problem seem too vague? I’ll show you a concrete example and a solution so you can see what I mean by including zero counts in SQL results. However, suppose you want to create a report that will also show data that has zero occurrences. But what if there are no occurrences of certain data? It will not show up in the result. ![]() It will count all the data it finds and return the number of occurrences. Using the COUNT() aggregate function is a reasonable first step. Here’s the problem: you want to count something that doesn’t exist, and you want to show your result as zero. Explaining how to include zero (0) counts in your SQL query result. ![]()
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