Ms access duplicated records - sql

Question

I`m having an issue with my MS Access query and I hope you can help me.
I want product "ABC" to have code "6029" if the parent is anything else than "GYF", "RGY" & "DRF".
The mapping looks as follows:
| Output_code | Account | Product | Parent |
+-------------+---------+----------+--------+
| 6029 | income | ABC | |
| 7029 | income | ABC | GYF |
| 7029 | income | ABC | RGY |
| 7029 | income | ABC | DRF |
+-------------+---------+----------+--------+
End result would be:
+-------------+---------+----------+--------+
| 6029 | income | ABC | DTF |
| 6029 | income | ABC | DHS |
| 7029 | income | ABC | GYF |
| 7029 | income | ABC | RGY |
| 7029 | income | ABC | DRF |
+-------------+---------+----------+-------
How it works right now:
+-------------+---------+----------+--------+
| 6029 | income | ABC | DTF |
| 6029 | income | ABC | DHS |
| 7029 | income | ABC | GYF |
| 7029 | income | ABC | RGY |
| 7029 | income | ABC | DRF |
| 6029 | income | ABC | GYF |
| 6029 | income | ABC | RGY |
| 6029 | income | ABC | DRF |
+-------------+---------+----------+--------+
Select A.*, B.Output_Code, "Product" as Comment from Source as A
inner join Mapping as B on (B.Account=A.Account and B.Product = A.Product)
where (B.Parent = "" or B.Parent <> A.Parent);
union all
Select A.*, B.Output_Code, "Product+Parent" as Comment from Source as A
inner join Mapping as B on (B.Account=A.Account and B.Product = A.Product
and A.Parent = B.Parent) where B.Parent <> "";
First part (Product) is not working as expected and combinations like ABC+RGY appear twice with both "6029" and "7029".
I tried using select within select (for this I introduced rowid) and it worked but right now is takes 30 min for my query to process (instead of 5 min).
Select A.*, B.Output_Code, "Product" as Comment from Source as A inner join
Mapping as B on (B.Account=A.Account and B.Product = A.Product)
where (B.Parent = "" or B.Parent <> A.Parent) and A.rowid not in (Select
A.rowid from Source as A inner join Mapping as B on (B.Account=A.Account and
B.Product = A.Product and A.Parent = B.Parent) where B.Parent <> "");
Could you kindly share your ideas on what is the proper way of building the first query so it doesn`t affect the performance so heavily?
I went through the list of questions but couldn`t find anything similar.

Answer 1

"Go for the simple solution, not the perfect one"
SELECT
IIF(Parent IN ('GYF','RGY','DRF'), 7029, 6029) as Output_code
FROM
Product
PS; i don't really do much Access SQL- i might not have used the correct string delimiters etc - you might need to jiggle this query around a bit
Edit: If you're looking to extend the mapping, you should consider a left join instead:
Select s.*, IIF(m.Output_Code IS NULL, 6029, m.output_Code)
FROM
source s
LEFT OUTER JOIN
mapping m
on (m.Account=s.Account and m.Product = s.Product and m.parent = s.parent)
Remove the 6029 row from the mapping table (redundant)
LEFT JOIN connects rows that match, and keeps rows from the left side (source) that don't have a match in the right (map) but puts nulls in the values for the right side. By comparison, an inner join throws away rows that don't have a match. It's the "this row from source has no match in map" quality that we want to leverage
This means the 'GYF','RGY','DRF' rows WILL have a match in the map table, they will not be null, the IIF will be false for those rows, the code from mapping will be used
Other rows will NOT have a match, the m.Output_code for those rows will be NULL, the IIF will be TRUE, the value 6029 will be used

Answer 2

I'll make a couple of assumptions about your base tables.
Your Mapping table looks like this:
| Output_code | Product | Parent |
|-------------|---------|--------|
| 7029 | ABC | DRF |
| 7029 | ABC | GYF |
| 7029 | ABC | RGY |
| 8593 | DEF | XYZ |
Your Source table looks like this:
| Product | Parent |
|---------|--------|
| ABC | DTF |
| ABC | DHA |
| ABC | GYF |
| ABC | RGY |
| ABC | DRF |
| DEF | XYZ |
| DEF | ZXL |
This SQL will return all your Source values with the correct Output_code attached. A Null value is returned where there is no Output_code:
SELECT Mapping.Output_code
, Source.Product
, Source.Parent
FROM Source LEFT JOIN Mapping ON Source.Product = Mapping.Product AND
Source.Parent = Mapping.Parent
| Output_code | Product | Parent |
|-------------|---------|--------|
| | ABC | DTF |
| | ABC | DHA |
| 7029 | ABC | GYF |
| 7029 | ABC | RGY |
| 7029 | ABC | DRF |
| 8593 | DEF | XYZ |
| | DEF | ZXL |
If the only product is ABC and you only want to to replace all NULL values with 6029 you could update the Mapping.Output_code line to NZ(Mapping.Output_code, 6029) to do this.
Nz Function help
SELECT NZ(Mapping.Output_code,6029)
, Source.Product
, Source.Parent
FROM Source LEFT JOIN Mapping ON Source.Product = Mapping.Product AND
Source.Parent = Mapping.Parent
| Expr1000 | Product | Parent |
|----------|---------|--------|
| 6029 | ABC | DTF |
| 6029 | ABC | DHA |
| 7029 | ABC | GYF |
| 7029 | ABC | RGY |
| 7029 | ABC | DRF |
| 8593 | DEF | XYZ |
| 6029 | DEF | ZXL |
But I expect you have more than one product and want product DEF to show a different value if there's no parent available.
To do this add a third table called NoMap that lists the code for any product that doesn't already have one:
| Product | Output_code |
|---------|-------------|
| ABC | 6029 |
| DEF | 7593 |
Primary Key: Product
You can then use this new table to replace any Null values found in your table:
SELECT NZ(Mapping.Output_code, NoMap.Output_code)
, Source.Product
, Source.Parent
FROM (
Source LEFT JOIN Mapping ON Source.Product = Mapping.Product AND
Source.Parent = Mapping.Parent)
LEFT JOIN NoMap ON Source.Product = NoMap.Product
| Expr1000 | Product | Parent |
|----------|---------|--------|
| 6029 | ABC | DTF |
| 6029 | ABC | DHA |
| 7029 | ABC | GYF |
| 7029 | ABC | RGY |
| 7029 | ABC | DRF |
| 8593 | DEF | XYZ |
| 7593 | DEF | ZXL |

Answer 3

You can use this.
Select A.*, NZ(B1.Output_Code, B2.Output_Code) as "Output_Code" from
(Source as A
left join Mapping as B1 on (B1.Account=A.Account and B1.Product = A.Product and B1.Parent = A.Parent ) )
left join Mapping as B2 on (B2.Account=A.Account and B2.Product = A.Product and (B2.Parent Is Null or B2.Parent ="") )