Can you make Querries/SELECT Statements from your own dataset?

[Denaes]

I havn't seen how to do it, but based on what I've read about datasets, it IS a replication of a database (full or partial) and this should be possible.

 

Anyone know?

[mr relaxo]

You can query datatables with the select method which returns an array of datarows.

 

eg

 

'fill a dataset named ds with a column named "itemId"
dim rows() as datarow
rows = ds.tables(0).select("itemId < 5")

[Denaes]

Can you use that like a full select statement?

 

"itemID<5 OR itemID>100"

 

That would cover really simple selects, but how about more complex ones, like when you want to populate another datatable with a combined relation of two tables?

 

Say I wanted to join MemberName and MemberBenefits at the MemberBenefitID column to have rows containing the member and their benefits?

 

I'm trying to cut back on querying the database for information I'm using when possible.

[bungpeng]

Just a suggestion: If possible, you better filter all the unnecessary data before insert to DataSet, to get the better performance of your system.

[Denaes]

And having to requery your database for every single procedure to get more/different results is going to be pretty bad for your performance.

 

I think there is some relevent data that you would want to keep in your dataset if you use it enough, and at that point it would be better to have all of the data that you'll use repeditivly on hand.

 

From there you might want to filter or extract that data further without requerying the database.

[bri189a]

The Find() functin is also helpful... I know I've done AND/OR in searching of a DataSet DataTable before I just can't remember if it was using the Find or the Select method....

[Bucky]

Also check out the DataView class for sorting and filtering data ros.