How to reteive data amongst defferent datatables

[Li Pang]

Hi,

I created a dataset that contains several datatables. I'd like to know how
to query data from these tables, like table join in sql?

thanks in advance

[Cor Ligthert [MVP]]

Li,

You cannot set a join on those tables, a dataset is not a database, however
you can set datarelations.

I hope this helps,

Cor

[Li Pang]

Cor Ligthert,

If there is a datarelation between the tables, can I get data concurrently
from the tables?

"Cor Ligthert [MVP]" wrote:

Li,

You cannot set a join on those tables, a dataset is not a database, however
you can set datarelations.

I hope this helps,

Cor

[Cor Ligthert [MVP]]

Li,

If there is a datarelation you can get any information from a parent and a
child.

http://msdn.microsoft.com/library/de...classtopic.asp

(However be aware AFAIK will not all databinding result in that what you
want. It gives back datarows and datarowcollections, not
datatable.defaultview by instance).

I hope this helps,

Cor

[Li Pang]

Thanks Cor Ligthert,

I know how to create a datarelationship. What I want to know is how to
retreiving data amongst the datatables between them there is already a
datarelationship. Shoul I go through row by row or I can create a dataview
and get at once?

http://eupmcchzugdev01.eu.pm.com:208.../WebForm1.aspx

"Cor Ligthert [MVP]" wrote:

Li,

If there is a datarelation you can get any information from a parent and a
child.

http://msdn.microsoft.com/library/de...classtopic.asp

(However be aware AFAIK will not all databinding result in that what you
want. It gives back datarows and datarowcollections, not
datatable.defaultview by instance).

I hope this helps,

Cor

[Cor Ligthert [MVP]]

Li,

You can in a datarow by instance to get the childrows

http://msdn.microsoft.com/library/de...drowstopic.asp

However as using the parentrow getting related rows and much more of that..

http://msdn.microsoft.com/library/de...trowstopic.asp

As I said, I am not lucky in using the dataview in combination with this.
(Maybe it can by creating a new table from the rows, however that I never
tried)

Cor

[Jay B. Harlow [MVP - Outlook]]

Li,
In addition to the other comments.

Although a DataSet does not support Joins directly, You can create a
JoinView as defined in the following KB article:

http://support.microsoft.com/kb/325682/EN-US/

Also once you define one or more DataRelation objects on your DataSet you
can use GetChildRows & GetParentRow & GetParentRows to get the rows for a
given relationship on a given DataRow.

Hope this helps
Jay

"Li Pang" <Li****@discussions.microsoft.com> wrote in message
news:26**********************************@microsof t.com...
| Hi,
|
| I created a dataset that contains several datatables. I'd like to know how
| to query data from these tables, like table join in sql?
|
| thanks in advance

[Emmet Gray]

On Thu, 1 Sep 2005 08:54:17 -0700, "Li Pang"
<Li****@discussions.microsoft.com> wrote:

Hi,

I created a dataset that contains several datatables. I'd like to know how
to query data from these tables, like table join in sql?

thanks in advance

I've recently completed a series of projects that will do exactly what
you're asking for. It will allow you to execute SQL select statements
(with join syntax) to query tables in a DataSet

Joining ADO.Net DataTables:
http://home.hot.rr.com/graye/Article...TableJoins.htm
In-Memory SQL Engine:
http://home.hot.rr.com/graye/Articles/SQL_Engine.htm

[Emmet Gray]

On Thu, 1 Sep 2005 08:54:17 -0700, "Li Pang"
<Li****@discussions.microsoft.com> wrote:

Hi,

I created a dataset that contains several datatables. I'd like to know how
to query data from these tables, like table join in sql?

thanks in advance

I've recently completed a series of projects that will do exactly what
you're asking for. It will allow you to execute SQL select statements
(with join syntax) to query tables in a DataSet

Joining ADO.Net DataTables:
http://home.hot.rr.com/graye/Article...TableJoins.htm
In-Memory SQL Engine:
http://home.hot.rr.com/graye/Articles/SQL_Engine.htm