Re: dataset merging

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

Aha!

the primary key property does the trick. When I merge now it does so based on the PK and I get the exact inclusive results I am after!

Many, many thanks!

: n)

"sloan" <sloan@xxxxxxxxx> wrote in message news:O6c3%23oZwIHA.4560@xxxxxxxxxxxxxxxxxxxxxxx

The dataset "merge" method can do about 2 things from my experience.

1. If you have N number of different datatables, it can merge the N number of tables into 1 (common) dataset.

2. If you have different ROWS, but the same table, you can merge the rows together. Most times, the rows will be different.

3. A combo of 1 and 2.

If you try to merge rows and the rows have the same primary key, but you're trying to merge columns of the same row, you'll have trouble.

Back to your question. You can't do what you're trying with a dataset. the .select and .merge methods are very very basic.

You need to look at LINQ. Or you'll have to loop and do your logic if you're in a pre 3.5 framework.

..



"Neil Chambers" <nospam@xxxxxxxxxx> wrote in message news:%234BjPkZwIHA.3760@xxxxxxxxxxxxxxxxxxxxxxx
I am trying to get my head around dataset merging but despite a little research I could still use a pointer (or ten). Basically I want to perform an outer join operation on a dataset (created from a file operation) and the resulting sql query based on the contents of said dataset. Effectively I would end up with two dataset tables in my application. If I were writing this to action from two tables it would be thus:



SELECT ds.id, db.*
from
dataset ds LEFT OUTER JOIN
database db on db.field1 = ds.id

such that I retain the original dataset items. I have read something about a dataset relationship but I do not see how this achieves the all-inclusive results I am after.

any insight much appreciated :-)

n



.

Relevant Pages

  • Re: SQL Subquery on Max(date)
    ... The overall query I'm trying to insert this select into ... LEFT OUTER JOIN ... CONSTRAINT pk_oncd_company ... PRIMARY KEY, ...
    (microsoft.public.access.formscoding)
  • Re: help
    ... An outer join is a join that allows you to retrieve ALL the records from ... About the primary key, I don't have the ... another table where I would only have one thing per employee ID, ... >> MS Access MVP ...
    (microsoft.public.access.queries)
  • Re: No duplicates
    ... You need what is called an Outer Join. ... colour - Text - Primary Key ... Jason Lepack ... ladybug via AccessMonster.com wrote: ...
    (microsoft.public.access.modulesdaovba)
  • Re: Lock at Record level or Page Level
    ... Check the plans of these two queries. ... Is your primary key clustered? ... A possible trick you could employ (assuming that it ...
    (microsoft.public.sqlserver.programming)
  • Re: Help on resolving record conflicts with ADO
    ... ADODataSet1.RecordSet.ReSync(adAffectCurrent, adResyncAllValues); ... Action:= daAbort; ... include any fields from another table through a left outer join (the other ... My select statement contains the primary key for the ...
    (borland.public.delphi.database.ado)