SQL: How to display data with row values as column names and then count number of times ID per row value?

Question

This is my database and fiddle setup:

CREATE TABLE PRODUCTS (
    NAME varchar(20),
    PRODUCT_ID int(3)
);

CREATE TABLE PAYMENT (
    NAME varchar(20),
    PAYMENT_ID int(4)
);

INSERT INTO PRODUCTS (NAME, PRODUCT_ID)
VALUES
("Apple", 1), 
("Banana", 2), 
("Watermelon", 3),
("Bread", 4), 
("Milk", 5), 
("Cake", 6), 
("Candy", 7), 
("Butter", 8), 
("Carrot", 9),
("Tomato", 10);


INSERT INTO PAYMENT (NAME, PAYMENT_ID)
VALUES
("Banana", 85),
("Apple", 94),
("Banana", 94),
("Candy", 85),
("Banana", 105);

https://www.db-fiddle.com/f/5jsGYfWZ6pnzgf62Z5FA8L/0

I'm thinking I have to do some Count(CASE statement within here).

I saw something about pivots, but not sure about that?

Answer 1

Yes you are right, that is a possibility

I use IF when there is only one option.

SELECT 
    p.NAME
    ,SUM(IF(PAYMENT_ID = 85,1,0)) '85'
    ,SUM(IF(PAYMENT_ID = 94,1,0)) '94'
    ,SUM(IF(PAYMENT_ID = 105,1,0)) '105'
FROM PRODUCTS p LEFT JOIN PAYMENT pa ON p.NAME = pa.NAME
GROUP BY p.NAME;

There Reference between the two tables should be the id and not the name, the name maybe unique, but numbers need less space than text.

 CREATE TABLE PRODUCTS ( NAME varchar(20), PRODUCT_ID int(3) ); CREATE TABLE PAYMENT ( NAME varchar(20), PAYMENT_ID int(4) ); INSERT INTO PRODUCTS (NAME, PRODUCT_ID) VALUES ("Apple", 1), ("Banana", 2), ("Watermelon", 3), ("Bread", 4), ("Milk", 5), ("Cake", 6), ("Candy", 7), ("Butter", 8), ("Carrot", 9), ("Tomato", 10); INSERT INTO PAYMENT (NAME, PAYMENT_ID) VALUES ("Banana", 85), ("Apple", 94), ("Banana", 94), ("Candy", 85), ("Banana", 105);

\n✓ \n\n✓ \n\n✓ \n\n✓ \n

SELECT p.NAME ,SUM(IF(PAYMENT_ID = 85,1,0)) '85' ,SUM(IF(PAYMENT_ID = 94,1,0)) '94' ,SUM(IF(PAYMENT_ID = 105,1,0)) '105' FROM PRODUCTS p LEFT JOIN PAYMENT pa ON p.NAME = pa.NAME GROUP BY p.NAME;

\nNAME | 85 |  94 |  105 \n:--------- |  -: |  -: |  --: \nApple | 0 |  1 |  0 \nBanana | 1 |  1 |  1 \nBread | 0 |  0 |  0 \nButter | 0 |  0 |  0 \nCake | 0 |  0 |  0 \nCandy | 1 |  0 |  0 \nCarrot | 0 |  0 |  0 \nMilk | 0 |  0 |  0 \nTomato | 0 |  0 |  0 \nWatermelon | 0 |  0 |  0 \n

db<>fiddle here

Answer 2

MySQL has a convenient shortcut. I recommend:

SELECT p.NAME,
       SUM(pa.PAYMENT_ID = 85) as payment_85,
       SUM(pa.PAYMENT_ID = 94) as payment_94,
       SUM(pa.PAYMENT_ID = 105) as payment_105
FROM PRODUCTS p LEFT JOIN
     PAYMENT pa
     ON p.NAME = pa.NAME
GROUP BY p.NAME;

Of course, if you don't care about products with no payments, you only need one table:

SELECT pa.NAME,
       SUM(pa.PAYMENT_ID = 85) as payment_85,
       SUM(pa.PAYMENT_ID = 94) as payment_94,
       SUM(pa.PAYMENT_ID = 105) as payment_105
FROM PAYMENT pa
GROUP BY pa.NAME;