1⟩ How do you register a component?
Compiling the component, running REGSVR32 MyDLL.dll
Visual Basic (VB)
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102 Visual Basic (VB) Questions And Answers
2⟩ Name the four different locking type in ADO and describe them briefly.
LockPessimistic Locks the row once after any edits occur.LockOptimistic Locks the row only when Update is called.LockBatchOptimistic Allows Batch Updates.LockReadOnly Read only. Can not alter the data.
3⟩ Name the four different cursor types in ADO and describe them briefly.
The cursor types are listed from least to most resource intensive.Forward Only Fastest, can only move forward in recordset Static Can move to any record in the recordset. Data is static and never changes.KeySet Changes are detectable, records that are deleted by other users are unavailable, and records created by other users are not detectedDynamic ? All changes are visible.
4⟩ What is Collection Objects in VB?
Similarly to arrays but is preferred over an array because of the following reasons.
1. A collection objects uses less Memory than an array.
2. It provides methods to add and delete members.
3. It does not required reason statement when objects are added or deleted.
4. It does not have boundary limitations.
5⟩ What are the Style properties of List Box in VB?
Simple Single Select , Extended. Multiple Select.
6⟩ What are the different ways to Declare and Instantiate an object in Visual Basic 6?
Dim obj as OBJ.CLASS with eitherSet obj = New OBJ.CLASS orSet obj = CreateObject(OBJ.CLASS?) orSet obj = GetObject( , OBJ.CLASS?)orDim obj as New OBJ.CLASS
7⟩ What does Option Explicit refer to?
All variables must be declared before use. Their type is not required.
8⟩ What is the tool used to configure the port range and protocols for DCOM communications?
DCOMCONFIG.EXE
9⟩ What two methods are called from the ObjectContext object to inform MTS that the transaction was successful or unsuccessful?
SetComplete and SetAbort.
10⟩ Why is it important to use source control software for source code?
Modification history.Code ownership: Multiple people can not modify the same code at the same time.
11⟩ Name and explain the different compatibility types when creating a COM component
No Compatibility ? New GUID created, references from other components will not workProject Compatibility ? Default for a new component Binary Compatibility ? GUID does not change, references from other components will work
12⟩ What is the difference between Property Get, Set and Let?
Set Value is assigned to ActiveX Object from the form.
Let Value is retried to ActiveX Object from the form.
Get- Assigns the value of an expression to a variable or property.
13⟩ How to change the Mouse Pointer?
Screen.MousePointer = VBHourGlass/VBNormal.
14⟩ Can We create CGI scripts in VB?
Yes we can create CGI scripts in VB
15⟩ What are the main components of the ADO object model? How are they used?
Connection: Used to make a connection between your app and an external data source, ie, sql server.Command: Used to build queries, including user-specific parameters, to access records from a data source (which are returned in a Recordset)Recordset:Used to access records returned from an SQL query. With a recordset, you can navigate returned records. You can also add, modify or delete records.
16⟩ Describe and In Process vs. Out of Process component. Which is faster?
An in-process component is implemented as a DLL, and runs in the same process space as its client app, enabling the most efficient communication between client and component.Each client app that uses the component starts a new instance of it.An out of process component is implemented as an EXE, and unlike a dll, runs in its own process space.
As a result, exe’s are slower then dll’s because communications between client and component must be marshalled across process boundaries. A single instance of an out of process component can service many clients.
17⟩ What is DBFailError?
Rolls Back updates if any errors Occurs.
18⟩ What is the benefit of wrapping database calls into MTS transactions?
If database calls are made within the context of a transaction, aborting the transaction will undo and changes that occur within that transaction. This removes the possibility of stranded, or partial data.
19⟩ What is Friend Variable?
Scope sharable between projects.
20⟩ What are some benefits of using MTS?
Database Pooling,
Transactional operations,
Deployment,
Security,
Remote Execution.
