Duplicate data

w0od0o · Jan 25, 2009

hi, i have created 3 queries and now i want to create a 4th to filter all the data to certain dates ect.. but when i add all 3 queries into 1 using all fields in the queries i get duplicate data,

i think it has something to do with the foreign keys but unsure on how to remove the problem,

thanks

w0od0o

Rabbie · Jan 25, 2009

You are going to have to give us some moe information. Details of your queries and your table structure as a minimum. Some real data would also be helpful.

w0od0o · Jan 26, 2009

here is a copy of my db, hope this helps

w0od0o · Jan 27, 2009

i have started my db again and changed quite a few things (for the better i hope

) but i was kinda hoping my problem with the duplicate data would have been an isolated issue but it appears i must be making the same mistakes as before,

i would be very grateful if someone could take a look at my new db and explain why im getting duplicate or false data

many thanks

w0od0o

Rabbie · Jan 27, 2009

Its very simple. Unless all the data sources are linked the query will generate a so-called cartesian join. This means that if you have 10 records in Table1 and 8 records in Table2 that unless they ae linked you get 80 records in the output.

w0od0o · Jan 28, 2009

so its more of a relationship issue than a query issue?

Rabbie · Jan 28, 2009

w0od0o said:
so its more of a relationship issue than a query issue?

Exactly. You need to make sure you have the correct joins in your query.

Duplicate data

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