Update table value by adding from other table - sql

Question

Can you please help me out with the below issue?
I have a table like below.
Table-1
Sales_RepID-- Name-- Products_Count
1-- ABC-- 2
2-- XYZ-- 4
3-- XXX-- 3
Table-2
Order_ID-- Sales_RepID-- Products_Count
1001-- 2 -- 2
1002-- 1 -- 1
1003-- 2 -- 1
1004-- 3 -- 3
1005-- 2 -- 2
Table - 1 Result
Sales_RepID, --Name, --Products_Count
1-- ABC --3
2-- XYZ --9
3-- XXX --6
I want to add table-2 Products_Count to Table-1 Products_Count for each Sale_RepID in the table-1
Can you please help with SQL Query?
My database is MS SQL SERVER

Answer 1

For MS SQL Server, please try:
UPDATE T
SET T.Products_Count=T.Products_Count+x.VSum
FROM Table1 T JOIN
(
SELECT DISTINCT
Sales_RepID,
SUM(Products_Count) OVER (PARTITION BY Sales_RepID) VSum
FROM
Table2
)x ON T.Sales_RepID=x.Sales_RepID

Answer 2

create table table1(sales_repId int,name varchar(10),product_count int);
create table table2(order_id int,sales_repId int,product_count int);
insert into table1 values(1,'ABC',2);
insert into table1 values(2,'XYZ',4);
insert into table1 values(3,'XXX',3);
insert into table2 values(1001,2,2);
insert into table2 values(1002,1,1);
insert into table2 values(1003,2,1);
insert into table2 values(1004,3,3);
insert into table2 values(1005,2,2);
select a.sales_repid,name,a.product_count+sum(b.product_count)
from table1 a
inner join table2 b
on a.sales_repid=b.sales_repid
group by a.sales_repid,name,a.product_count
order by a.sales_repid
UPDATE
update table1
set product_count = netProduct
from (
select a.sales_repid,name,a.product_count+sum(b.product_count) as netProduct
from table1 a
inner join table2 b
on a.sales_repid=b.sales_repid
group by a.sales_repid,name,a.product_count
) z
inner join table1 x
on z.sales_repid=x.sales_repid

Answer 3

TRY THIS
DECLARE #TABLE1 AS TABLE( Sales_RepID INT,Name VARCHAR(100), Products_Count int)
DECLARE #TABLE2 AS TABLE( Order_ID INT,Sales_RepID INT, Products_Count int)
INSERT INTO #TABLE1
VALUES(1,'ABC',2),(2,'XYZ',4),(3,'XXX',3)
INSERT INTO #TABLE2
VALUES(1001,2,2),(1002,1,1),(1003,2,1),(1004,3,3),(1005,2,2)
SELECT * FROM #TABLE1
SELECT * FROM #TABLE2
UPDATE T1
SET T1.Products_Count = T1.Products_count + total
FROM #TABLE1 T1
CROSS APPLY (
SELECT total= sum(Products_count)
FROM #Table2 T2
WHERE T1.Sales_RepID =t2.Sales_RepID ) Z

Answer 4

To output as a select:
select
t1.Sales_RepID,
t1.Name,
t1.Products_Count + sum(t2.Products_Count)
from table1 t1
left join table2 t2 on t2.Sales_RepID = t1.Sales_RepID
To update the total in table1, adding the total from table2:
update table1 set
Products_Count = Products_Count + (
select sum(Products_Count)
from table2
where Sales_RepID = table1.Sales_RepID)
These queries will work in all SQL dialects.
MS SQL Server has a special syntax for updating using a join, which will perform much better than the universal update syntax above:
update t1 set
t1.Products_Count = t1.Products_Count + t2.Products_Count
from table1 t1
join (select Sales_RepID, sum(Products_Count) Products_Count
from table2
group by Sales_RepID) t2
on t2.Sales_RepID = t1.Sales_RepID;
See a live demo of this update statement executing on SQLFiddle.
Note that this is an unusual query. Typically, such denormalized values are not cumulative: they are a determinable calculated value, which in this case wold be simply the sum, not the existing value plus the sum. Your design means that the query can only be executed once. After than you'll be repeatedly re-adding the total from table2.
Consider redesigning your tables to have the straight sum from table2 in table1, ie:
update t1 set
t1.Products_Count = t2.Products_Count
from table1 t1
join (select Sales_RepID, sum(Products_Count) Products_Count
from table2
group by Sales_RepID) t2
on t2.Sales_RepID = t1.Sales_RepID;