How to Improve Get_ROW_NUMBER with correlated

Question

How to Improve this query please:
SELECT     FatherID, Date, Line, ProductCode, StockCode, QtyIn, QtyOut,
                          (SELECT     SUM(QtyIn - QtyOut) AS Expr1
                             FROM         (SELECT     ROW_NUMBER() OVER (ORDER BY Date, ID) AS Line, *
FROM         Test1) AS t1
                             WHERE     (Line <= t0.Line) AND (ProductCode = t0.ProductCode) AND (StockCode = t0.StockCode)) AS total, Type
FROM         dbo.test2 AS t0
test2 is a view:
SELECT     ROW_NUMBER() OVER (ORDER BY Date, ID) AS Line, *
FROM         Test1

Answer 1

Please post DDL, so that people do not have to guess what the keys, constraints, Declarative Referential Integrity, data types, etc. in your schema are. Learn how to follow ISO-11179 data element naming conventions and formatting rules. Ypu have no idea
and ths is full of errors. Temporal data should use ISO-8601 formats. _code should be in Standard SQL AS much AS possible and not local dialect. 
This is minimal polite behavior on SQL forums. 
What little you did give us is wrong. DATE is both a reserved word in SQL, and too vague to be a column name. It looks like that vague “line” is a physical line on a print out. RDBMS does not have a generic “id”; we use logic and the Law of Identity while you
have Kabbalah numbers and magic. You have the the father of someone and their blood type in this mess. Well, why not “blood_type”, since there is no generic “<something>_type”
Nesting scalar subqueries will kill performance; there is no general way to optimize them. 
Why do you order the data with ROW_NUMBER() then sum it? A summation does not depend on ordering. I will guess that your mindset is still locked in physical files that have to be ordered -– punch cards and mag tapes. 
If you want a running total, here is a query without DDL, just like you gave us.
SELECT stock_date, product_id, 
       SUM(input_qty - output_qty) 
       OVER (PARTITION BY stock_date, product_id
             ORDER BY stock_date
             ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)
       AS daily_stock_level
  FROM Inventory;
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