DataRelation Object vs. INNER JOIN

Posted on 2004-10-21
Last Modified: 2008-02-01
Being new to C# (about 1 week), I saw that there is a DataRelation object in ADO.Net.  From what I have gathered so far is that one can add multiple tables into a DataSet and use the DataRelation object to establish the relationship between the tables inside the same DataSet.  

Now, what I am wondering is:  Isn't that what inner joins are for?  If so, when would one use a DataRelation Object as opposed to an INNER JOIN?


Question by:brdrok
    LVL 20

    Expert Comment

    Inner joins are used in selects inside the database. In most cases the two tables have also a relation, but this is not obligatory.

    The relationship object shows a relation in your dataset. Based on this relation you can programmatically get all child records or the parent record in this relation, however all objects must be pre-loaded from the database.
    LVL 7

    Author Comment

    thanks a lot....i suppose one uses the datarelation object when, for example, showing the parent-child(ren) records inside a datagrid?!?

    on a totally different subject (if you need more points, let me know)....

    if one has applied the rowFilter and filtered the dataset according to whatever there a method that will allow the programmer (me in this case hehehehe....) to restore the default/original view w/o having to clear and "re-load" the dataset?


    LVL 20

    Accepted Solution

    Just set the RowFilter to null - this will clear it
    LVL 7

    Author Comment

    cool beans...thanks...

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