MySQL - how to dynamically add columns with subquery in Select clause based on date range

Question

I have the following statetment:

 Select a.Data AS Data_A,b.Data AS Data_B,
(Select Round(Sum(C.Value)) From Values c 
 Where 
 (Year(c.TimeStamp) = x) and 
 (Month(c.TimeStamp) = y)
) AS MonthYear
From Table1 a Left Join Table2 b on (a.ID = b.ID)

Ist there any way to add a column to the select clause based on my desired range of date? (where Year(c.TimeStamp) < 2019 and Month(c.TimeStamp) <= 12)

Example1 - i want to see the data for 1 month:

Select a.Data AS Data_A,b.Data AS Data_B,
(Select Round(Sum(C.Value)) From Values c 
 Where 
 (Year(c.TimeStamp) = 2018) and 
 (Month(c.TimeStamp) = 1)
) AS Jan2018
From Table1 a Left Join Table2 b on (a.ID = b.ID)

Example2: i want to see the data for 3 months

Select a.Data AS Data_A,b.Data AS Data_B,
(Select Round(Sum(C.Value)) From Values c 
 Where 
 (Year(c.TimeStamp) = 2018) and 
 (Month(c.TimeStamp) = 1)
) AS Jan2018,
(Select Round(Sum(C.Value)) From Values c 
 Where 
 (Year(c.TimeStamp) = 2018) and 
 (Month(c.TimeStamp) = 2)
) AS Feb2018,
(Select Round(Sum(C.Value)) From Values c 
 Where 
 (Year(c.TimeStamp) = 2018) and 
 (Month(c.TimeStamp) = 3)
) AS Mar2018
From Table1 a Left Join Table2 b on (a.ID = b.ID)

I hope my question is understandable. :)

Thank you for reading.

• Michael Kutz: Something tells me 2018 is not a valid Month()
• Huppel: @MichaelKutz - so true :) Thank you. It's edited.

Answer 1

You must construct different queries to get 1 column of output versus 3 columns. That is best done in your application language. If you are trying to do it entirely in SQL, it would require a messy Stored Procedure.