Question

Id       Item
--------------
1        ItemA 
2        ItemB
3        ItemC

itemid     Price
----------------
1          4
1          3
1          9
2          2
2          4
2          3

How I can select with sum from 2 tables? Like as:

ItemA 16
ItemB 9
ItemC 0

Answer 1

You can JOIN the table using a LEFT JOIN and apply an aggregate function SUM() to the price field:

select t1.item, IsNull(sum(t2.price), 0) total
from table1 t1
left join table2 t2
  on t1.id = t2.itemid
group by t1.item

See SQL Fiddle with Demo

The LEFT JOIN will allow for the records not in the second table to be included in the final result. I added the IsNull() to the sum() to replace any null values with a zero.

Result:

|  ITEM | TOTAL |
-----------------
| ItemA |    16 |
| ItemB |     9 |
| ItemC |     0 |