Manipulating Datasets

[Anil Gupte]

How can I manipulate Datasets, such as getting a specific row based on a key
column value. Of course, I could loop through all the rows in the entire
dataset each time I needed something, but is there an easier way? I want to
be able to execute the equivalent of SQL statements including insert, delete
etc.

Any ideas? Thanx,
--
Anil Gupte

https://www.keeninc.net

https://www.icinema.com

[sloan]

Re: Manipulating Datasets


You have to

1. Perform a .Select
2. Change the data
3. (Sometimes) commit the changes



Let's say you have a strong dataset called EmployeeDS with an
Employee(table) . EmpID(int),Last Name(string),Fi rstName(string)


EmployeeDS ds = //populate the ds somehow with employees

DataRow[] rows = ds.Select("EmpI D=123");
//vb dim rows as DataRows() = ds.Select("EmpI D=123");
//or
//DataRow[]rows = ds.Select("Last Name='Smith'");
//or vb
//dim rows as DataRows() = ds.Select("Last Name='Smith'");

now you have an array of rows

you loop over them, but you'll have to cast them

dim i as integer
for i = 0 to rows.Length - 1 //or .Count?
EmployeeDS.Empl oyeeRow currentRow = ctype(rows(i),
EmployeeDS.Empl oyeeRow
currentRow.Last Name = "Jones" //change the data

next i

Console.Writeli ne (ds.GetXml())



Something like that.





"Anil Gupte" <anil-list@icinema.co mwrote in message
news:uz%232TvTf IHA.1824@TK2MSF TNGP02.phx.gbl. ..

How can I manipulate Datasets, such as getting a specific row based on a
key column value. Of course, I could loop through all the rows in the
entire dataset each time I needed something, but is there an easier way?
I want to be able to execute the equivalent of SQL statements including
insert, delete etc.
>
Any ideas? Thanx,
--
Anil Gupte

https://www.keeninc.net

https://www.icinema.com

>
>

[Steve Gerrard]

Re: Manipulating Datasets

Anil Gupte wrote:

I thought DataViews were read-only? I am using VB.Net 2003
>

How so? A DataView is just a another look at rows in a DataTable.

Some ways to modify data in through a DataView:

Dim DV As DataView = New DataView(MyTabl e)
DV.Item(3).Item ("CheckFlag" ) = 1

Dim drv As DataRowView
drv = DV.Item(3)
drv("CheckFlag" ) = 1

For Each drv In DV
drv("CheckFlag" ) = 1
Next drv

Dim nID As Integer = 23
dv.Sort = "EmpID"
drv = dv.FindRows(nID ).GetValue(0)
drv("CheckFlag" ) = 1

' etc...

[Cor Ligthert[MVP]]

Re: Manipulating Datasets

Steve,

It's a mini-database. :)

It is certainly not or should add to your text, "single user", this has
given very much misunderstandin gs in past.

One of the disadvantages is than even that you have to read and write
forever the complete XML file while it is not changeble on disk.

Cor

[Cor Ligthert[MVP]]

Re: Manipulating Datasets

Anil-

A little addition to your two other answers,

http://msdn2.microsoft.com/en-us/library/bb386977.aspx

-Cor

"Anil Gupte" <anil-list@icinema.co mschreef in bericht
news:uz%232TvTf IHA.1824@TK2MSF TNGP02.phx.gbl. ..

How can I manipulate Datasets, such as getting a specific row based on a
key column value. Of course, I could loop through all the rows in the
entire dataset each time I needed something, but is there an easier way?
I want to be able to execute the equivalent of SQL statements including
insert, delete etc.
>
Any ideas? Thanx,
--
Anil Gupte

https://www.keeninc.net

https://www.icinema.com

>
>

[Anil Gupte]

Re: Manipulating Datasets

From Sams Teach Yourself Visual Basic in 21 Days on page 714:

"Dataviews are much like read-only datasets. Because they're read-only,
they work like snapshots of your data, and they provide you with faster
access to that data than datasets can. The term "data view" means just
that - a view of your data - and they're usually used as containers for a
subset of your data."

--
Anil Gupte

https://www.keeninc.net

https://www.icinema.com

"Steve Gerrard" <mynamehere@com cast.netwrote in message
news:LqKdnXt8b_ YaV1HanZ2dnUVZ_ hynnZ2d@comcast .com...

Anil Gupte wrote:

>I thought DataViews were read-only? I am using VB.Net 2003
>>

>
How so? A DataView is just a another look at rows in a DataTable.
>
Some ways to modify data in through a DataView:
>
Dim DV As DataView = New DataView(MyTabl e)
DV.Item(3).Item ("CheckFlag" ) = 1
>
Dim drv As DataRowView
drv = DV.Item(3)
drv("CheckFlag" ) = 1
>
For Each drv In DV
drv("CheckFlag" ) = 1
Next drv
>
Dim nID As Integer = 23
dv.Sort = "EmpID"
drv = dv.FindRows(nID ).GetValue(0)
drv("CheckFlag" ) = 1
>
' etc...
>
>