Avoiding duplicates in query

[theracer06]

Hi,

I am trying to refine a query for a simulation I inherited. The query forms one duplicate for each row.

In the picture attached are the three joined tables used for the query.

What is wrong here?

I tried Select Distinct, but it seems not to be working.

SELECT [Load curves].[ID Country], Years.Year, [Load curves].Date, [Load curves].Time, [Load in MW]*[Annual Load increase] AS [Projected Load in MW], Years.Year-[Value] AS [Years difference], Year(Now()) AS [Current year], Parameters.Value
FROM [Parameters], ([Load curves] INNER JOIN [Annual Load Increase] ON [Load curves].[ID Country]=[Annual Load Increase].[ID Country]) INNER JOIN Years ON [Annual Load Increase].Year=Years.Year;

[weekend00]

make sure there is no duplicate values in the join fields.

If you mean [Load in MW]*[Annual Load increase] are "duplicate" as your expectation(result is double/ triple), assume [Load in MW] and [Annual Load increase] are in table [load curves] then make sure [Annual Load Increase].[ID Country]) and Years.Year don't have duplicate values.

And, you should not just put table Parameters in the query without any condition, this will general as many duplicate records as the number of records in parameter table.

To make it easy to understand what I said, I give a simple example:

Table AA Table BB
A1, A2 B1 B2
1 2 1 gg
3 3 1 dd
4 5

There are duplicate value in BB.B1, so
select AA.* from AA inner join BB on AA.a1=BB.b1
will return 2 records as:
A1 A2
1 2
1 2

select AA.* from BB,AA
will return 6 records:
A1 A2
1 2
1 2
3 3
3 3
4 5
4 5

Try to modify you query as what you understand.