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abc
Level: Guest

Declare an istance of object

Hello
I'm starting to learn VB.Net
When working with ADO I have to declare some objects and variables.
There are some syntax in declare statements that I don't understand, for example:

Dim Reader1 As SQLClient.SQLDataReader (1)
Dim DataAdapter As New sqlClient.SqlDataAdapter() (2)
Dim myCommand As New SqlCommand(sqlSelect, myConnection) (3)
Reader1 = New Command1.ExecuteReader (4)
.....

I don't know
- When to use "As" like in (1)
- When to use "As New"
and in this case when I can have no parameter like in (2)
or when I can have parameter like in (3)
- When to use "= New" like in (4)

Thanks for any help

16-09-2002 at 03:37 AM

dcostelloe
Level: VB Guru

Registered: 11-06-2002
Posts: 74

Re: Declare an istance of object

quote:
abc wrote:
Hello
I'm starting to learn VB.Net
When working with ADO I have to declare some objects and variables.
There are some syntax in declare statements that I don't understand, for example:

Dim Reader1 As SQLClient.SQLDataReader (1)
Dim DataAdapter As New sqlClient.SqlDataAdapter() (2)
Dim myCommand As New SqlCommand(sqlSelect, myConnection) (3)
Reader1 = New Command1.ExecuteReader (4)
.....

I don't know
- When to use "As" like in (1)
- When to use "As New"
and in this case when I can have no parameter like in (2)
or when I can have parameter like in (3)
- When to use "= New" like in (4)

Thanks for any help

Well to start there are books written on the subject to avoid writing a book on the subject :-)

(1)
New:
Creates a New Instance of the object

AS
Creates a instance of the object.
(2)
If I were to use the the above in ASP.Net I would use the New keyword to create a New Instance of the object for each user(Page) that calls it:
Dim ds As DataSet = New DataSet()
Each Page called will get a new instance of the object.

A good sample of variables are shown in the .Net Framework help

ms-help://MS.VSCC/MS.MSDNQTR.2002APR.1033/vbcn7/html/vacondeclaringvariables.htm

(3)
Dim myCommand As New SqlCommand(sqlSelect, myConnection)
Creates a New Instance of the object SQLCommand which now you are passing parameters to the class
(4)
Reader1 = New Command1.ExecuteReader
Your Object Reader is creating a new instance of the of the comand object and applying the values to the dataReader

Hope this Helps

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17-09-2002 at 11:57 PM

AndreaVB Forum : VB.Net : Declare an istance of object


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