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Update field in one table by looking it in second table.

Posted on 2009-05-15
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Last Modified: 2012-05-07
Well there just one problem. the second table may have multiple entries. so consider table A

table A:

ROLLNUMBER   NAME
111                     na
111                     na

TABLE B:

ROLLNUMBER  ALIAS NAME
111                    GM     GAURAV
111                    MAN   GAURAV
111                    GAU   GAURAV


NOW I NEED TO UPDATE NAME IN TABLE A LOOKING IT UP IN TABLE B. INNER JOIN WILL GIVE ME 6 ENTRIES BUT I NEED JUST THE NAME SO AFTER UPDATE I SHOULD HAVE JUST 2 ROWS IN TABLE A.

THANKS



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Question by:mandelia
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Author Comment

by:mandelia
ID: 24396051
Dont worry the names are not not different and even if they are something like  First(name)  will solve my purpose
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Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24396055
syntax depends on the database product/version you use,
please clarify

note: please do not post with ALL CAPS ON...
that's usually considered shouting...
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Author Comment

by:mandelia
ID: 24396196
right now MS Access.
 
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Author Comment

by:mandelia
ID: 24396203
oh ok that was not intentional
 
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Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 2000 total points
ID: 24396222
what about this
UPDATE TABLEA
  SET NAME = DLOOKUP("NAME", "TABLEB", "ROLLNUMBER = " & ROLLNUMBER)

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LVL 5

Author Comment

by:mandelia
ID: 24396274
thanks for the frist part how do in do this in MS SQL  server 2005.
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Author Comment

by:mandelia
ID: 24396319
moreover is there a query that can do the same on multiple servers
0
 
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Author Comment

by:mandelia
ID: 24396324
i mean database independent
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Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24396362
in sql, this would be:
UPDATE a
  SET Name = b.Name
FROM TABLEA a
 JOIN TableB b
  on B.RollNumber = a.RollNumber

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Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24396367
in oracle:
UPDATE a
  SET Name = (SELECT b.Name FROM TableB b WHERE B.RollNumber = a.RollNumber and rownum = 1 )
FROM TABLEA a

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LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24396382
in mysql:
UPDATE TableA a, TableB b
  SET a.Name = b.Name
WHERE B.RollNumber = a.RollNumber

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Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24396398
>i mean database independent
no way, sorry.

the best is you put that code in a stored procedure, so "all" you have to do to make the application "portable" is to change/adjust the stored procedures ...
0
 
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Author Comment

by:mandelia
ID: 24396410
but B.RollNumber = a.RollNumber will return 3 rows
wont it create a problem
 
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Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24396483
no.
0
 
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Author Comment

by:mandelia
ID: 24396608
tried  ....
 
UPDATE [TABLEA]
SET NAMEA = DLOOKUP ("NAMEB","TABLEB". "rollB =" & rollA)
 
as column names in table a are rollA and NameA
and in tableB are nameB and rollB
 
 
It gives me invalid use of '.','!' or '()'. in query expression 'DLOOKUP ("NAMEB","TABLEB". "rollB =" & rollA'.
0
 
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Author Comment

by:mandelia
ID: 24396740
i have more than 1M rows so using update and Dlookup in VBA is out of question.
i think it will take a lot of time
0
 
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Author Comment

by:mandelia
ID: 24396778
sorry my fault there was a . insteed of , after tableB.
 
It worked
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Author Closing Comment

by:mandelia
ID: 31581933
Brilliant
0
 
LVL 5

Author Comment

by:mandelia
ID: 24396886
The query ran fine but didnot update giving a type conversion error.  All fields here is text any idea what can it be
0
 
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Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24396925
> All fields here is text any idea what can it be
UPDATE [TABLEA]
SET NAMEA = DLOOKUP ("NAMEB","TABLEB". "rollB = """ & rollA & """ ") 
  

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