SQL sum up sales volume for different customer locations - sql

Question

I'm using Oracle SQL-developer and I got the following output-table, which shows the monthly sales value of our customers. The customers have several locations.
month
year
customer_name
sales_volume
01
2022
Farming company Berlin
150
01
2022
Farming company London
200
01
2022
Farming company Amsterdam
350
01
2022
XY Company Berlin
200
01
2022
customer 5
7
01
2022
customer 7
7
01
2022
X_Person
2
02
2022
XY Company London
100
02
2022
Hello Company Berlin
150
02
2022
Hello Company Amsterdam
150
02
2022
customer 1
20
02
2022
customer 2
10
02
2022
customer 3
5
02
2022
Y-Person
1
Now I'd like to get the sales_volume per customer_name for month/year. I want to add the sales_volume per month/year for all the different locations of the Farming company, the XY Company and the Hello Company. The rest (customer 1-7, X-Person, Y-Person) should be summed up in an own row named "Other"
The new output table would be the following:
month
year
customer_name
sum_Sales_volume
01
2022
Farming Company
700
01
2022
XY Company
300
01
2022
Other
16
02
2022
XY Company
100
02
2022
Hello Company
300
02
2022
Other
36
So far I tried to sum the customer_name with LIKE function but I don't understand how the "when then" works in this case.
My code:
Select
month,
year,
sum(sales_volume)
CASE
WHEN customer_name LIKE '%Farming%' Then 'Farming Company'
WHEN customer_name LIKE '%XY%' Then 'XY Company'
WHEN customer_name LIKE '%Hello%' Then 'Hello Company'
ELSE THEN 'Standard'
END AS "sum_Sales_volume"

Answer 1

I don't understand how the "when then" works in this case.
In a LIKE comparison, % is a wildcard character that matches zero-or-more of any character.
So, for WHEN customer_name LIKE '%Farming%', you are testing to see if the customer_name value has:
The start-of-the-string; then
Zero-or-more of any character; then
The sub-string Farming; then
Zero-or-more of any character; and
Finally, the end-of-the-string.
If it matches then the value of the THEN clause of the CASE expression is returned; otherwise the next WHEN clause is tested and so on until if none of the WHEN clauses are matched then the value from the ELSE clause is returned.
how can I sum up the values from the sales_volume column based on this string I'm searching in customer name.
Just use your CASE expression in the GROUP BY clause:
Select month,
year,
CASE
WHEN customer_name LIKE '%Farming%'
THEN 'Farming Company'
WHEN customer_name LIKE '%XY%'
THEN 'XY Company'
WHEN customer_name LIKE '%Hello%'
THEN 'Hello Company'
ELSE 'Standard'
END AS customer_name,
sum(sales_volume) AS sum_sales_volume
FROM table_name
GROUP BY
month,
year,
CASE
WHEN customer_name LIKE '%Farming%'
THEN 'Farming Company'
WHEN customer_name LIKE '%XY%'
THEN 'XY Company'
WHEN customer_name LIKE '%Hello%'
THEN 'Hello Company'
ELSE 'Standard'
END;

Answer 2

As MTO already answered the question, but from the comment it seems there are some more things to explain I'll try to clarify some possible missunderstandings about LIKE() function with % wildcard and especially about CASE expression. All of the below code and results refers to your sample data.
% wildcard character stands for (replaces) none or any string/array of characters
Oracle character comparisons are case sensitive
Just a few samples:
Select A_NAME From tbl Where A_NAME Like('%Berlin%'); -- any string containing 'Berlin' -with first capital letter
-- Result: Farming company Berlin
-- XY Company Berlin
-- Hello Company Berlin
Select A_NAME From tbl Where A_NAME Like('%berlin%'); -- any string containing 'berlin' -with first small letter
-- Result: no rows selected
Select A_NAME From tbl Where A_NAME Like('%1'); --any string that ends with character '1' -including just '1'
-- Result: customer 1
Select A_NAME From tbl Where A_NAME Like('cust%3'); --any string starting with 'cust' and ending with '3'
-- Result: customer 3
Select A_NAME From tbl Where A_NAME Like('Far%on'); -- any string starting with 'Far' and ending with 'on'
-- Result: Farming company London
CASE expresssion - the most important thing to know is the fact that CASE evaluates WHEN conditions until the first one satisfied (True). When that happens CASE returns the value and ends checking possible other WHEN conditions. It is very important to have this in mind when using CASE with multiple WHEN conditions.
In the below code compare two CASE expressions selected - with coresponding values of columns DESCRIPTION_1 and DESCRIPTION_2. The ressulting differences are more than obvious and the only difference between the CASE expressions used is the order of WHEN conditions.
Select A_MONTH, A_YEAR, A_NAME, VOLUME,
CASE WHEN VOLUME >= 100 THEN '100 plus'
WHEN VOLUME >= 200 THEN '200 plus'
WHEN VOLUME >= 300 THEN '300 plus'
ELSE 'less than 100'
END "DESCRIPTION_1",
CASE WHEN VOLUME >= 300 THEN '300 plus'
WHEN VOLUME >= 200 THEN '200 plus'
WHEN VOLUME >= 100 THEN '100 plus'
ELSE 'less than 100'
END "DESCRIPTION_2"
From tbl
/* R e s u l t :
A_MONTH A_YEAR A_NAME VOLUME DESCRIPTION_1 DESCRIPTION_2
------- ---------- ------------------------- ---------- ------------- -------------
01 2022 Farming company Berlin 150 100 plus 100 plus
01 2022 Farming company London 200 100 plus 200 plus
01 2022 Farming company Amsterdam 350 100 plus 300 plus
01 2022 XY Company Berlin 200 100 plus 200 plus
01 2022 customer 5 7 less than 100 less than 100
01 2022 customer 7 7 less than 100 less than 100
01 2022 X_Person 2 less than 100 less than 100
02 2022 XY Company London 100 100 plus 100 plus
02 2022 Hello Company Berlin 150 100 plus 100 plus
02 2022 Hello Company Amsterdam 150 100 plus 100 plus
02 2022 customer 1 20 less than 100 less than 100
02 2022 customer 2 10 less than 100 less than 100
02 2022 customer 3 5 less than 100 less than 100
02 2022 Y-Person 1 less than 100 less than 100
*/
Hopefuly this could help you to better understand the % wildcard, LIKE() function and CASE expression and what to have in mind combining them.
Regards...