Lesson 16
Weather Observation Station 16  SQL Aggregation  HackerRank Solution
Summary
Weather Observation Lesson Summary
In this lesson, we're focusing on querying a database for weather observation data. Here's a concise breakdown of the key points discussed:
Database Table
 Table Name:
station
 Columns:
ID
city
state
lat_n
long_w
Objective
 Task: Query the smallest
lat_n
value that is greater than38.778
.  Output Requirement: Round the result to four decimal places.
Steps to Achieve the Query

Visualize the Data:
 Execute the command:
SELECT * FROM station;
 Focus on the
lat_n
column values.
 Execute the command:

Filter and Find Minimum:
 Use a
WHERE
clause to filterlat_n
for values greater than38.778
.  Retrieve the smallest value:
 Use
MIN(lat_n)
to find the minimum latitude after filtering.
 Use
 Use a

Round the Result:
 Apply the
ROUND
function to format the result to four decimal places.
 Apply the
Final Result
 The query yields:
38.8526
(rounded to four decimal places).
This method effectively identifies the smallest latitude from the selected observations over the specified threshold.
Video Transcript
Hey everybody, welcome back to another lesson.
I will do weather observation, station 16 on the section aggregation from SQL Hacker
Rink.
We're given the table station that has five columns ID, city, state, lat, underscore,
n, long underscore, w.
We're asked to query the smallest lat underscore, n that is greater than 38.778.
So around the answer to four decimal places.
Okay, so let's get started.
So I always like to visualize the data.
So I say select star from station, run code.
Okay, so here for the purposes of this question, we only care about the column,
lat, underscore, n, these values here.
So for the range that's greater than 38.778, what value is the lowest, right?
You have to find the lowest out of all these numbers.
So let's go.
We here have to say, aware.
First, lat underscore n has to be greater than 38.778.
And then we have to take, okay, so we have the lat underscore n values.
And we have to take the smallest.
And for that, we could do an order by and take only the row of the smallest.
The first one if you do ascending, or you could use the function min.
So I'm gonna use min of lat underscore n.
So out of all the values that were found, it takes the smallest one.
And because we want to round the answer to four decimal places,
if you think this is one thing that's the actual value of the min,
you have to say round for the function call.
And two decimal places has to be four here for four decimal places.
And there you go, we have 38.8526, exactly four digits to the righthand side of
the decimal point, and it was being rounded.
And that's weather observation station 16.
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