Question

In: Electrical Engineering

Explain the following code. What language? What does it do? What is the result? SELECT date_trunc('month',date),avg(value)...

Explain the following code. What language? What does it do? What is the result?

SELECT date_trunc('month',date),avg(value)

FROM rain

GROUP BY date_trunc ('month',date)

ORDER BY date_trunc('month',date);

Solutions

Expert Solution

It is PostgreSQL.

The code can be explained as PostgreSQL Date functions.

The DATE_TRUNC function rounds a timestamp value to a specified interval, which allows you to count events. Here you can round off a timestamp.

The DATE_TRUNC syntax looks like this: DATE_TRUNC('interval',timestamp).

For example, SELECT DATE_TRUNC('day','2015-04-12 14:44:18') would return a result of 2015-04-12 00:00:00.

You can isolate the month of the visit with DATE_TRUNC.

SELECT DATE_TRUNC('month',occurred_at) AS month
  FROM demo.web_events
 WHERE occurred_at BETWEEN '2015-01-01' AND '2015-12-31 23:59:59'

To return a count of web visits each month by channel, add the channel column and a COUNT to the SELECT statement, then group by month and channel. (Since month and channel are the first two values in your SELECT statement, you can GROUP BY 1,2), like this:

SELECT DATE_TRUNC('month',occurred_at) AS month,
       channel,
       COUNT(id) AS visits
  FROM demo.web_events
 WHERE occurred_at BETWEEN '2015-01-01' AND '2015-12-31 23:59:59'
 GROUP BY 1,2

Finally, use ORDER BY 1,2 to organize your results chronologically (by month) and alphabetically (by channel).

SELECT DATE_TRUNC('month',occurred_at) AS month,
       channel,
       COUNT(id) AS visits
  FROM demo.web_events
 WHERE occurred_at BETWEEN '2015-01-01' AND '2015-12-31 23:59:59'
 GROUP BY 1,2
 ORDER BY 1,2    

In Mode, you can build a line chart to visualize the query results.

Here, from the given code we can plot the graph between the rain avg value to the specific month.

Date will be truncked here.


Related Solutions

Explain the following code. What language? What does it do? What is the result? SELECT date_trunc('month',date),avg(value)...
Explain the following code. What language? What does it do? What is the result? SELECT date_trunc('month',date),avg(value) FROM rain GROUP BY date_trunc ('month',date) ORDER BY date_trunc('month',date);
Explain the following code. What language? What does it do? What is the result?                 <!DOCTYPE...
Explain the following code. What language? What does it do? What is the result?                 <!DOCTYPE teo[                                 <ELEMENT teo((stations| databases)+)>                                 <ELEMENT stations(stationName stationLocation sensors*)> <ELEMENT databases(databaseName databaseType )> <ELEMENT stationName(#PCDATA)> <ELEMENT stationLocation(#PCDATA)> <ELEMENT sensors (sensorName phenomenon)+> <ELEMENT sensorName(#PCDATA)> <ELEMENT phenomenon(#PCDATA)> <ELEMENT databaseName(#PCDATA)> <ELEMENT databaseType(#PCDATA)> <!ATTLIST stations boundingBox CDATA #required> ]>
What does language do for its speaker? explain, be specific!
What does language do for its speaker? explain, be specific!
Python 3 Fix the code so if the user does not select a value in the...
Python 3 Fix the code so if the user does not select a value in the sold by field, it shows a warning message indicating "Choose one value" import tkinter as tk from tkcalendar import DateEntry from openpyxl import load_workbook window = tk.Tk() window.title("daily logs") window.grid_columnconfigure(1,weight=1) window.grid_rowconfigure(1,weight=1) # labels tk.Label(window, text="Bar code").grid(row=0, sticky="W", pady=20, padx=20) tk.Label(window, text="Products failed").grid(row=1, sticky="W", pady=20, padx=20) tk.Label(window, text="Money Lost").grid(row=2, sticky="W", pady=20, padx=20) tk.Label(window, text="sold by").grid(row=3, sticky="W", pady=20, padx=20) tk.Label(window, text="Failed date").grid(row=4, sticky="W", pady=20, padx=20) #...
Write a MIPS assembly language program that implements the following pseudo-code operation: result = x +...
Write a MIPS assembly language program that implements the following pseudo-code operation: result = x + y – z + A[j] x and y should be in reserved memory words using the .word directive and labeled as x and y. Initialize x=10 and y=200. Read in z from the console. Input the value -8. This is the value for z, not for –z. Store this value in memory with the label z. To begin, you could just initialize z to...
I'm having trouble understanding the following code (a snippet of a code). What does it do?...
I'm having trouble understanding the following code (a snippet of a code). What does it do? The whole code is about comparing efficiencies of different algorithms. def partition(list,first,last): piv = list[first] lmark = first+1 rmark = last done = False while not done: while lmark <= rmark and list[lmark]<=piv: lmark=lmark+1 while list[rmark]>=piv and rmark>=lmark: rmark=rmark-1 if rmark<lmark: done = True else: temp = list[lmark] list[lmark]=list[rmark] list[rmark]=temp temp = list[first] list[first]=list[rmark] list[rmark]=temp return rmark
How does growth occur as a result of knowing our value? What qualities in people do...
How does growth occur as a result of knowing our value? What qualities in people do you admire most?
1) What is BLAST? What does it do? What is in a BLAST "result"? What is...
1) What is BLAST? What does it do? What is in a BLAST "result"? What is an "alignment" in the case of BLAST? 2) There is always a symbol indicating a relationship between each pairwise amino acid in the query and subject; what do the different symbols mean? "+" vs "-" vs " " vs "<a specific letter matching letter>"
Arduino Uno code, Please explain what does this code do? unsigned long ms_runtime; int one_ms_timer; //define...
Arduino Uno code, Please explain what does this code do? unsigned long ms_runtime; int one_ms_timer; //define all timers as unsigned variables unsigned long timer1 = 0; // timer1 increments every 100ms = 0.1s const int USER_LED_OUTPUT = 13; const int USER_BUTTON_INPUT = 2; void setup() { // initialize the digital pin as an output. pinMode(USER_LED_OUTPUT, OUTPUT); pinMode(USER_BUTTON_INPUT, INPUT); Serial.begin(9600); } void loop() { // run loop forever static int state, old_state,counter; timers(); // logic for state change if(state == 0)...
Translate the following C code into M4K assembly language. You do not have to use the...
Translate the following C code into M4K assembly language. You do not have to use the frame pointer, just use $sp if you need to use the stack. You do not have to show the stack initialization nor stack cleanup. If you need a specific value for an address, just make an assumption. int A; main() { int B = 5; B = A+B }; // main //Disassembly starts here !main() { //stack and frame pointer init // you do...
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT