Visual Basic (VB) Interview Questions And Answers

Compiling the component, running REGSVR32 MyDLL.dll

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

Modification history.Code ownership: Multiple people can not modify the same code at the same time.

SetComplete and SetAbort.

DCOMCONFIG.EXE

All variables must be declared before use. Their type is not required.

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

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.

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.

This allows MTS to reuse database connections. Database connections are put to sleep as opposed to being created and destroyed and are activated upon request.

Provide a scenario using three of them to return data from a database. Expected answer: Connection Connects to a data source; contains the Errors collectionCommand Executes commands to the data source. Is the only object that can accept parameters for a stored procedure.Recordset The set of data returned from the database.Scenario: There are many possibilities. The most likely is as follows:Dim conn As ADODB.ConnectionDim rs As ADODB.RecordsetDim Cmd As ADODB.Commandconn.ConnectionString = ?CONNECTION STRING?conn.OpenSet Cmd.ActiveConnection = connCmd.CommandText = ?SQL STATEMENT?Set rs = Cmd.ExecuteSet rs.ActiveConnection = Nothingconn.Close

The Parameters collection.

Database Pooling,
Transactional operations,
Deployment,
Security,
Remote Execution.

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.

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.

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.

Yes we can create CGI scripts in VB

X as variant and y as integer.

Writing function and calling it when error occurs.

When some controls like grid and third party control placed in our application then it will create frx in run time.

Vbrun300.dll

To list the hierarchical list of the node objects. Such of files and Directories.

This will call the top most error where the error is handled.

This cannot have user interface. This can be used for the COM creation.

The Variant data type has a numeric storage size of 16 bytes and can contain data up to the range of a Decimal, or a character storage size of 22 bytes (plus string length),and can store any character text.