[VB .NET]Dataset Into An Array

[+John Teacake MVC]

I have a dataset (Comes from an SQL Database) in VB .NET I need to put into an array so I can play around with it (And pass it to a webchart but thats a different story). How do I go about doing this? I cant seem to find a way to get the data from the dataset into an array :cry:

Also whats the difference between a Dataset,Datatable and DataView?

[James Rose]

Ok, this code is for VB Classic, so it wont take much change

DIM i as integer

Dim arValues(0) as string 'or whatever your data types are.

i = 1

Do while NOT rs.EOF

Redim PRESERVE arValue(i) 'Preserve is important here!

arValues(i) = rs.Fields(0).Value

i = i + 1

rs.MoveNext

Loop

But I sonder why your control cannot be populated by the dataset/resultset/recordset directly?

Peace,

James

[+John Teacake MVC]

  jameswjrose said:

Ok, this code is for VB Classic, so it wont take much change

DIM i as integer

Dim arValues(0) as string 'or whatever your data types are.

i = 1

Do while NOT rs.EOF

Redim PRESERVE arValue(i) 'Preserve is important here!

arValues(i) = rs.Fields(0).Value

i = i + 1

rs.MoveNext

Loop

But I sonder why your control cannot be populated by the dataset/resultset/recordset directly?

Peace,

James

You mean the webchart control?

[James Rose]

  Sawyer12 said:

You mean the webchart control?

yes, Im surprised the Webchart control does not have another entry point other than an array.

It seems a waste of time to take data out of a heavy array (recordset/dataset/etc) into a lightweight array, and then place that data into the webchart control.

But since I dont know the control and it's capabilities... I'm talking out my... well, you get the idea.

Best of luck

[+John Teacake MVC]

I need to do some playing around with the data before I use it.

[James Rose]

  Sawyer12 said:

I need to do some playing around with the data before I use it.

Ok. I still use Datasets/Recordsets. I can update, sort, filter and do many more things with these heavy arrays than I can do EASILY with standard arrays.

But hey, that's just me.

[azcodemonkey]

  Sawyer12 said:

I have a dataset (Comes from an SQL Database) in VB .NET I need to put into an array so I can play around with it (And pass it to a webchart but thats a different story). How do I go about doing this? I cant seem to find a way to get the data from the dataset into an array :cry:

Also whats the difference between a Dataset, Datatable and DataView?

A DataSet is a collection of data, generally DataTables.

A DataTable is just that; an in memory representation of a data table. It has primary keys, relationships, types, rows, columns, etc.

A DataView is a read-only view of a DataTable. You'll probably want to use this if you're iterating thru it to populate an array, or forgo the Dataset altogether and use a DataReader and read into an array. A DataReader is a read-only, forward-only recordset which has far less overhead than a DataSet. In your case, you'd use a SqlDataReader.

Do you need to put only one particular field into an array, or the entire table?

' using a SqlDataReader
Dim reader As SqlDataReader = command.ExecuteReader()
Dim items As new List(Of String) ' or Of whatever type you need

while(reader.Read())
	' get col by name
	' items.Add( reader("username") )
	' or by index
	items.Add( reader(0) ) ' gets the value for the first column
end while

[LRoling]

Does the Dataset have one value per row, or multiple values per row? If multiple values per row, and you want these in the array, here:

  Quote

For x As Integer = 0 To ds.Tables(0).Rows.Count -1

MyArray(x, 0) = ds.Tables(0).Rows(x)(0)

MyArray(x, 1) = ds.Tables(0).Rows(x)(1)

MyArray(x, 2) = ds.Tables(0).Rows(x)(2)

Next

You could do a simple piece of code like this, number of lines depending on number of values in a Datarow.

[+John Teacake MVC]

  LRoling said:

Does the Dataset have one value per row, or multiple values per row? If multiple values per row, and you want these in the array, here:

You could do a simple piece of code like this, number of lines depending on number of values in a Datarow.

Why the -1 on the end?

[James Rose]

The -1 line would make a little more sence with parathese

For x As Integer = 0 To (ds.Tables(0).Rows.Count -1)

For example let's say your data set has 10 rows

Since you start at ZERO in the loop, and you need to go for 10 trips through the loop (the count value) zero to nine is ten trips. Since arrays are zero based your array would have the values 0, 1, 2... 8, 9

Get it? Good.