Rick
Mon Jan 02 15:20:54 CST 2006
Thanks! I am actually using the same dataset over & over for multiple uses.
With an ADO recordset, once the recordset was closed then I could use it for
something totally different (different query with different schema) with no
problem. Fortuneately the coding that I have been doing the last few days I
included a .Clear immediately after I was finished with the dataset. I was
remembering the DAO days when there was NO warning within any sample at all
about requiring a separate workspace and database for every recordset or
they could trash each other. So I started wondering how much of the same
trouble I might have with datasets as every example that I have seen simply
pulls in a set of data for a silly reason then does nothing else. This
latest version of .Net (2005) the VB samples are far better, but still don't
address multiple data accesses very well. I guess that is what experience
is all about, but the samples could help there.
Thanks again,
Rick
"W.G. Ryan - MVP" <WilliamRyan@nospam.gmail.com> wrote in message
news:uFOEKA%23DGHA.1120@TK2MSFTNGP11.phx.gbl...
>
> "Rick Lederman" <rick@soaringsoftware.com> wrote in message
> news:OQUY419DGHA.336@TK2MSFTNGP14.phx.gbl...
>> Is a DataSet.Clear required before new data is brought into the dataset?
> --It depends.
>>
>> I.E. daMyDataset.Fill(dsMyDataset)
>>
>> Can I simply refill the dataset with new data intended to totally replace
>> the old data, or must I do a .Clear first?
>
> If you have a Key on the Table and you use the same query, then you can
> refresh it. However if youdon't have a key on the table, then it will add
> duplicates of the rows.
>
>
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemdatacommondbdataadapterclassfilltopic.asp
>
> Here's a summary of the rules to have it refresh vs fill over again:
>
> When using subsequent Fill calls to refresh the contents of the DataSet,
> two conditions must be met:
>
> 1.. The SQL statement should match the one initially used to populate the
> DataSet.
> 2.. The Key column information must be present.
> If primary key information is present, any duplicate rows are reconciled
> and only appears once in the DataTable that corresponds to the DataSet.
> Primary key information may be set either through FillSchema, by
> specifying the PrimaryKey property of the DataTable, or by setting the
> MissingSchemaAction property to AddWithKey.
>>
>> Thanks
>>
>> Rick Lederman
>>
>
>