Alfredo
Search results
May 10, 2017 · Can I do a max(count(*)) in SQL? Yes , you can achieve that by nesting an aggregate function in a window function : SELECT m.yr , count(*) AS movie_count , max(count(*)) OVER () AS max_ct FROM casting c JOIN movie m ON c.movieid = m.id WHERE c.actorid = (SELECT id FROM actor WHERE name = 'John Travolta') GROUP BY m.yr ORDER BY count(*) DESC;
Apr 20, 2024 · In this page we are discussing the usage of SQL COUNT() along with the SQL MAX(). The sql having also be used with sql max function.
- Before We Start…
- SQL Functions to Aggregate Data
- SQL Count function. Let’s Count Lines!
- SQL Sum function. Calculate Sum!
- SQL Avg function. Calculate Averages… I Mean The *Mean*.
- SQL Max and Min Functions. Let’s Get Maximum and Minimum values.
- SQL Group by – For Basic Segmentation Analysis and More…
- Test Yourself #1
- Test Yourself #2
- SQL Order by – to Sort The Data Based on The Value of One
…I recommend going through these articles first – if you haven’t done so yet: 1. Set up your own data server: How to set up Python, SQL, R, and Bash (for non-devs) 2. Install SQL Workbench to manage your SQL queries better: How to install SQL Workbench for PostgreSQL 3. Read the first two episodes of the SQL for Data Analysis series: ep 1 and ep 2 ...
Okay, let’s open SQL Workbench and connect to your data server! Can you recall our base query? It was: And it returned the first 10 lines of this huge data set. We are going to modify this query to get answers to 5 important questions: 1. How many lines are there in our SQL table? (We’ll use the SQL COUNTfunction for that.) 2. What’s the total airt...
The easiest aggregation function is to count lines in your SQL table. And this is what the COUNT function is for. The only thing you have to change – compared to the above base query – is what you SELECT from your table. Remember? It can be everything (*), or it can be specific columns (arrdelay, depdelay, etc). Now, let’s expand this list with fun...
Now we want to get the airtime for all flights – added up. In other words: get the sum of all values in the airtime column. The SUM function works with a similar logic as COUNT does. The only difference is that in the case of SUM you can’t use * — you’ll have to specify a column. In this case, it’ll be the airtimecolumn. Try this query: The total a...
Our next challenge is to calculate the average arrival delay value and the average departure delay value. It’s important to know that there are many types of statistical averages in mathematics. But we usually refer to the average type called mean — when we say “average” in everyday life. (A quick reminder: mean is calculated by calculating the sum...
And finally, let’s find the maximum and the minimum values of a given column. Finding the maximum and minimum distances for these flights sounds interesting enough. SQL-syntax-wise, MIN and MAX operate just like SUM, AVG and COUNTdid. Here’s the minimum distance: Result: 11 miles. (Man, maybe take the bike next time.) Result: 4962 Okay! That was it...
SQL GROUP BY – the theory
As a data scientist, you will probably run segmentation projects all the time. For instance, it’s interesting to know the average departure delay of all flights (we have just learned that it’s 11.36). But when it comes to business decisions, this number is not actionable at all. However, if we turn this information into a more useful format – let’s say we break it down by airport – it will instantly become something we can act on! Here’s a simplified chart showing how SQL uses GROUP BYto crea...
SQL GROUP BY – in action
Here’s a query that combines an SQL AVG function with the GROUP BYclause — and does the exact thing that I described in the theory section above: Fantastic! If you scroll through the results, you will see that there are some airports with an average departure delay of more than 30 or even 40 minutes. From a business perspective, it’s important to understand what’s going on at those airports. On the other hand, it’s also worth taking a closer look at how the good airports (depdelay close to 0)...
Here’s a little assignment to practice! Let’s try to solve this task and double-check that you understand everything so far! It’s simple: Print the total airtime by month! . . . Ready? Here’s my solution: I did pretty much the same stuff that I have done before, but now I’ve created the groups/segments based on the months – and this time I had to u...
And here’s another exercise: Calculate the average departure delay by airport again, but this time use only those flights that flew more than 2000 miles (you will find this info in the distance column). . . . Here’s the query: There are two takeaways from this assignment. 1. You might have suspected this but now it’s confirmed: you can use the SQL ...
Let’s say we want to see which airport was the busiest in 2007. You can get the number of departures by airport really easily using the COUNT function with the GROUP BYclause, right? We have done this before in this article: The problem: this list is not sorted by default… To have that too, you need to add one more SQL clause: ORDER BY. When you us...
SELECT MAX(count) FROM (SELECT COUNT(docname) FROM doctor GROUP BY docname) a; This is all the doctors and how many patients they have: SELECT docname, COUNT(docname) FROM doctor GROUP BY name;
Sep 30, 2013 · I'd try with a ORDER BY max DESC LIMIT 1, where maximum is the count (*) field. Something like: SELECT "name", count(*) maximum FROM "users". INNER JOIN "microposts" ON "microposts"."user_id" = "users"."id". GROUP BY users.id.
Jan 26, 2024 · COUNT Function. The COUNT function returns the number of rows matching a certain criteria. Here’s an example that counts all the rows in the table: SELECT COUNT(*) as total_rows FROM sales; Output: +-----+ | total_rows | +-----+ | 6 | +-----+ The table contains a total of 6 rows.
People also ask
What is a count function in SQL?
How do you use a count function?
Can I use Max with a limit?
How do I add a maxcount to a docname in CTE?
How to get maximum number of agents as column alias'mycount'?
Which query produces maximum number of agents mentioned as'mycount'?
Oct 21, 2021 · The COUNT() function is one of the most useful aggregate functions in SQL. Counting the total number of orders by a customer in the last few days, the number of unique visitors who bought a museum ticket, or the number of employees in a department, can all be done using the COUNT() function.
