Create table and get data from another table - sql

Question

I have a table Cost category:
CREATE TABLE [dbo].[CostCategory](
[ID_CostCategory] [int] NOT NULL,
[Name] [varchar](150) NOT NULL,
[Plan] [money] NOT NULL,
[Realization] [money] NULL,
)
go
and I have another table with defined Costs:
CREATE TABLE [dbo].[Cost](
[ID_Cost] [int] NOT NULL,
[Name] [varchar](50) NULL,
[ID_CostCategory] [int] NULL,
[ID_Department] [int] NULL,
[ID_Project] [int] NULL,
[Value] [money] NULL,
)
go
What I want to do is to sum values from Cost table (according to ID_CostCategory) and put into Cost Category table, Realization column. So each ID_CostCategory presents automaticaly sum of Costs from Cost table (per ID_CostCategory).
How can I modify the script of Cost Category table to achieve it? Probably it's not a rocket science but I am really new to SQL.
OK. One more thing I forgot to add...
the structure looks in a way:
Cost>Cost Category>Department>Project
Right now I can easily take data from cost table and present it in Cost Category table. But Cost table includes such data as:
ID_Cost Name ID_CostCategory ID_Department ID_Project Value
1 fv 001 1 1 1 100
2 fv 002 2 1 1 500
3 fv 003 2 2 1 300
4 fv 004 3 2 2 150
5 fv 005 3 3 2 30
6 fv 006 4 3 2 15
I have also table Department which includes colums: ID_Department, Name, Plan,
So now, I want to do is to sum values from Cost table (according to ID_CostCategory and ID_Department) and put into Department table as Realization column. So each ID_Department presents automaticaly sum of Costs from Cost table (per ID_CostCategory and ID_Department).
Hope it is clear (later on will have to do it with table Project, but once I got it, it will be easy)

Answer 1

Try this
--create table without realization column
CREATE TABLE [dbo].[CostCategory](
[ID_CostCategory] [int] NOT NULL,
[Name] [varchar](150) NOT NULL,
[Plan] [money] NOT NULL
) go
CREATE TABLE [dbo].[Cost](
[ID_Cost] [int] NOT NULL,
[Name] [varchar](50) NULL,
[ID_CostCategory] [int] NULL,
[ID_Department] [int] NULL,
[ID_Project] [int] NULL,
[Value] [money] NULL,
) go
Create a UDF to calculate sum of the cost column:
CREATE FUNCTION [dbo].[CalculateRealization](#Id INT)
RETURNS money
AS
BEGIN
DECLARE #cost money
SELECT #cost = SUM(Value)
FROM [dbo].[Cost]
WHERE [ID_CostCategory] = #ID
return #cost
END
Now Alter your CostCategory table to add computed column:
ALTER TABLE [dbo].[CostCategory]
ADD [Realization] AS dbo.CalculateRealization(ID_CostCategory);
Now you can select Realization from Costcategory
SELECT ID_CostCategory, Realization
FROM [dbo].[CostCategory]
Answer to your comment below:
Create Another UDF
CREATE FUNCTION [dbo].[CheckValue](#Id INT, #value Money)
RETURNS INT
AS
BEGIN
DECLARE #flg INT
SELECT #flg = CASE WHEN [Plan] >= #value THEN 1 ELSE 0 END
FROM [dbo].[CostCategory]
WHERE [ID_CostCategory] = #ID
return #flg;
END
Now add Constraint on Cost Table:
ALTER TABLE ALTER TABLE [dbo].[Cost]
ADD CONSTRAINT CHK_VAL_PLAN_COSTCATG
CHECK(dbo.CheckValue(ID_CostCategory, Value) = 1)

Answer 2

You do not need to have a Realization column as part of the CostCategory table. Rather, you will want to use a join.
Select A.ID_CostCategory, A.Name, SUM(B.Value) As Realization from CostCategory A
JOIN Cost B ON A.ID_CostCategory = B.ID_CostCategory
Group By A.ID_CostCategory, A.Name