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conditional update query

Posted on 2011-03-22
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Last Modified: 2012-06-27
I have 2 ms access 2003 tables with the following sample data

table a
id      Floater
1      
2    
3
4


table b
id      Floater
1      N
3      Y

Note: there is only one entry for a given id on both tables
          there may be id entries on table a that are not on table b

I am trying to write an update query that will  update the value of floater on table a

 if there is an matching id entry on table b I would like the value of floater on table a to be set to that on table b


If there is no matching id entry on table b I would like the floater value on table a to be set to N

using the example data I would like table a to have the following values after the update query is run


table a
id      Floater
1      N
2      N
3      Y
4      N
0
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Question by:johnnyg123
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6 Comments
 
LVL 77

Expert Comment

by:peter57r
ID: 35192402
update tableA set floater = nz(Dlookup("Floater", "TableB","Id = " & tableA.Id) , "N")
0
 

Author Comment

by:johnnyg123
ID: 35192573
I have the access query prompts on

when I run the query I get a message saying it is going to update 4 records but then when I click ok
I get an error message that says

Microsoft Office Access can't update all the records in the update query

Microsoft office access didn't update 4 field(s) due to a type conversion failure

0
 

Author Comment

by:johnnyg123
ID: 35192605
I have attached a sample database
test.mdb
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LVL 17

Expert Comment

by:JezWalters
ID: 35192703
You'll need the following, because the id fields are text:

    UPDATE tablea
    SET floater = Nz(DLookup("floater", "tableb", "id = """ & id & """"), "N")

0
 
LVL 26

Expert Comment

by:Nick67
ID: 35193350
@JezWalters is right
String variables need to be surrounded by quotes
But, gazillions of quotes drive me mad and are VERY hard to debug
Chr(34) is a quote mark
Works in VBA and the query editor

This works and is easier to digest
UPDATE tableA
SET tableA.floater = nz(DLookUp("Floater","TableB","Id = " & Chr(34) & tableA.Id & Chr(34)),"N");

Chr(34) & tableA.Id & Chr(34) is your text field id surrounded by quotes
0
 
LVL 17

Accepted Solution

by:
JezWalters earned 500 total points
ID: 35196884
If you don't like the fact that you have to double each quotation mark when it's inside quotation marks, you could always use apostrophes instead.

Whichever delimiter you use, but bear in mind that you'll also have to double any ocuurences of it in your id values too!
UPDATE tablea
SET floater = Nz(DLookup("floater","tableb","id = '" & id & "'"),"N")

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