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Query with IF's (SQL)

Posted on 2011-02-23
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Last Modified: 2012-05-11
I have a table with 5 fields.

FriendYN
EnemyYN
SellingPrice1
SellingPrice2
SellingPrice3

I want a query with 1 output field only.

The logic is as follows;

If EnemyYN="Y" and FRIENDYN<>"Y" select SellingPrice1
If FriendYN="Y" then select SellingPrice2
Else
Select sellingprice 3

How do I write this SQL?

(As a tangental question!  As a general rule would the experts prefer to receive a sample database attached with queries like this??  Is it more or less hassle to receive an attached database?)
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Question by:Patrick O'Dea
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Accepted Solution

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Patrick Matthews earned 350 total points
ID: 34965209
I like using Switch for this, as explained in http://www.experts-exchange.com/Microsoft/Development/MS_Access/A_3556-Using-the-Switch-Function-in-Microsoft-Access.html


SELECT Switch(EnemyYN = "Y" And FriendYN <> "Y, SellingPrice1, EnemyYN = "Y", SellingPrice2, True, SellingPrice3) AS Result
FROM SomeTable

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Getting a sample database is very often helpful, especially if there is any complexity to the request :)
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Assisted Solution

by:borki
borki earned 150 total points
ID: 34965288
A sample database helps a lot - because in a scenario like yours, the best way to give you advise is by tweaking with a bit of data...

You could write a query field with IIF or SWITCH statements. However, i the logic gets complicated I prefer to write your own user defined function in VBA and call it from a query.

So the function would look like this

Public Function SellPrice(FriendYN As Variant, EnemyYN As Variant, Price1 As Variant, Price2 As Variant Price3 As Variant) As Variant
<insert your query code logic, as in the original question>
End Function

Then write a query such as:

SELECT SellPrice([FriendYN], [EnemyYN], [SellingPrice1], [SellingPrice2], [SellingPrice3]) AS Price
FROM <table>
WHERE <criteria>

HTH
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Author Closing Comment

by:Patrick O'Dea
ID: 34965419
Thanks!

The switch is new to me!

Very useful too.
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Expert Comment

by:Patrick Matthews
ID: 34965804
21Dewsbury,

Glad to help!  If you have not already done so, I would really appreciate it if you could please return to my article
http://www.experts-exchange.com/Microsoft/Development/MS_Access/A_3556-Using-the-Switch-Function-in-Microsoft-Access.html
and click 'Yes' for the 'Was this helpful?' voting.

Patrick
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