How to create new column and new row based on two tables? - mysql

Question

I have two tables:
Table 1
MARKET ATC3 ATC4 PRODUCT BOOLEAN FLAG JOINING COLUMN
A1 B1 B1C1 D1 1 ATC4
A2 B1 B1C2 D2 1 ATC4
A2 B1 B1C3 ATC4
FAMILY A B1 ATC3
Table 2:
PRODUCT ATC3 ATC4 VALUES
D1 B1 B1C1 10
D1 B1 B1C1 20
D2 B1 B1C2 15
D2 B1 B1C2 25
D2 B1 B1C2 10
D3 B1 B1C3 5
My desired output:
PRODUCT ATC3 ATC4 VALUES MARKET VALUES
D1 B1 B1C1 10 A1 10
D1 B1 B1C1 20 A1 20
D2 B1 B1C2 15 A2 15
D2 B1 B1C2 25 A2 25
D2 B1 B1C2 10 A2 10
D3 B1 B1C3 5 A2 5
ALL D1+D2+D3 FAMILY A 85
The idea is, Table 2 has many rows and products but does not have Market. Table 1 helps you find out which product in Table 2 belongs to which Market-based on the Joining column. For example, There are 3 Markets present in Table 1, I want to then assign a new column Market in Table 2 such that all PRODUCTS in Table 2 with the ATC4 code of B1C1 belongs to the Market A1. Why? Because in Table 1, it says that Market A1 should follow the Joining Column of ATC4 - which corresponds to the code B1C1. In Table 1, we also provided a Product column, this is just for our purpose of identifying our own companies product name. Now if you see that for Table 1, there are two rows of Market A2, with different ATC4, this is very normal, because maybe Product D2 and D10 belong to Market A2, but both may contain different ATC4!
There is also one more nuance to it, we have Family A! This is merely a combination of A1+A2, but in my Table 2, there is no such row value that sums up to Family A. So I need to achieve two things:
I want to make a new column Market in Table 2 so that each product is mapped to the market.
I want to create extra rows to account for the Market Family A (A1+A2) and call the product Name "Lovely Family A" or something. The above table 3 provides an expected output.
Since I am new to SQL, I tried to first use CASE Statements, to map slowly one by one, but soon it gets tedious and I wonder if there's some tricks.
My CASE looks like this
,CASE WHEN ATC4 LIKE '%B1C1%' THEN 'A1'
WHEN ATC4 LIKE '%B1C2%' OR ATC4 LIKE '%B1C3%' THEN 'A2' ELSE ATC4 END AS MARKET_NAME
but have yet to figure out how to add the additional row where I can sum up A1+A2.

Answer 1

You seem to want something like this:
with rows as (
select PRODUCT, ATC3, ATC4, VALUES
from table2
union all
select 'ALL D1+D2+D3', ATC3, NULL, SUM(VALUES)
from table2
group by ATC3
)
select r.*, t1.market
from rows r join
table1 t1
on (t1.joining_column = 'ATC3' and t1.atc3 = r.atc3) or
(t1.joining_column = 'ATC4' and t1.atc4 = r.atc4);
I see no reason to repeat the values column. And values is a really bad name for a column because it is a SQL keyword.