Question

I have the following table :

group_id    amount  type
1           10      1
1           2       1
1           5       2
1           4       3
2           5       1

and I am looking for a view that will aggregate the data in this table such that the view produces something like this and can hopefully do it in a dynamic way:

group_id    type1_amount    type2_amount    type3_amount
1           12              5               4
2           1               NULL            NULL

My preference is to use a view in MySQL (if you have a better option I am open to hear it) and the big restriction of views in MySQL is that sub selects in the FROM clause are not allowed.

Answer 1

SELECT
    group_id,
    SUM(CASE WHEN type = 1 THEN amount END) AS type1_amount,
    SUM(CASE WHEN type = 2 THEN amount END) AS type2_amount,
    SUM(CASE WHEN type = 3 THEN amount END) AS type3_amount
FROM your_table
GROUP BY group_id