SQL SUM Group by - based on 'group' from another table - sql

Question

I hope I am explaining this correctly.
I have 2 tables, with
first table (table1)
+------------+------+-------+-------+
| Date | Item | Block | Total |
+------------+------+-------+-------+
| 2017-01 | a1 | B1 | 10.0 |
| 2017-01 | a2 | B1 | 20.0 |
| 2017-01 | a3 | B2 | 30.0 |
| 2017-02 | a1 | B1 | 40.0 |
| 2017-02 | a2 | B1 | 50.0 |
| 2017-02 | a3 | B2 | 60.0 |
+------------+------+-------+-------+
second table (table2)
+------------+------+
| Item Group | Item |
+------------+------+
| IG1 | a1 |
| IG1 | a2 |
| IG2 | a2 |
| IG2 | a3 |
+------------+------+
*Note that, one item group has multiple items.
The items may appear several time in different item groups.
Now, I need to sum the total (table1), based on Item Group (table2), Date and Block, in the end, final table:
+---------+------------+-------+-------+
| Date | Item Group | Block | Total |
+---------+------------+-------+-------+
| 2017-01 | IG1 | B1 | 30.0 |
| 2017-01 | IG2 | B1 | 20.0 |
| 2017-01 | IG1 | B2 | 0.0 |
| 2017-01 | IG2 | B2 | 30.0 |
+---------+------------+-------+-------+
How to achieve this with SQL query?
EDIT:
OK. It seems that this is an easy one. Shame on me. I didn't know the join and Group By can be applied that way. SQL is really awesome. That saves tons of coding.

Answer 1

A join and a simple group by should work for you in this case:
select t1.Date, t2.ItemGroup, t1.Block, sum(t1.Total) Total
from table1 t1 join table2 t2 on t1.Item = t2.Item
group by t1.Date, t2.ItemGroup, t1.Block

Answer 2

Simple group by after a join
SELECT f.date, s.[Item Group], f.[Block], Total = sum(f.Total) from firsttable f
INNER JOIN secondtable s
ON f.item = s.item
GROUP BY f.date, s.[Item Group], f.[Block]

Answer 3

We can use Window Clause Over() and Partition By to achieve this. Since your query is straight forward and used all the columns in select list and Group by clause, we can use a simple join and Group by clause.
Anyways here is the query using Over Clause:
select DISTINCT t1.dateyear, t2.ItemGroup, t1.Block,
sum(Total) over(PARTITION BY t2.ItemGroup, t1.dateyear, t1.Block) as GroupTotal
FROM tab_1 t1
JOIN tab_2 t2
ON t1.Item = t2.Item

Answer 4

I have a similar question. I want to select data from a table based on another table.
This is what I have:
Table1
Articlename, group, status
Table2
Articlename, date
This is what I want:
If an article in Table1 has a group and status=1 Count posts in Table2 between date1 and date2, group result by the group in Table1
The result should look something like this
Group Quantity
-----------------
GR1 250
GR2 50
GR3 110