What is view Port? What are the different types of error? What is the diff between the Std and Class Module? What is Mixed Cursors? Drag and Drop state numbers and functions? What are the Style Properties of Combo Box? What are the Style properties of List Box? What is Collection Objects? What is the difference between Property Get, Set and Let? How to change the Mouse Pointer? What is Friend Variable? What is DBFailError? What are the record set types? What is the diff between RDO and ADO? Diff types of Lock Types? What are the scopes of the class? Have you create Properties and Methods for your own Controls? Private Dim x as integer. Valid ? Different type of Instantiation? What are the different types of Dialog Box? What is Seek Method which type of record set is available this? What is Zorder Method? Can us able to set Instancing properties like Singleuse, GlobalSingleuse to ActiveXDll? What are properties available in Clip Board? What is the different between Microsoft ODBC Driver and Oracle OBDC Driver? What the RDO Methods and Events? What is MAPI ? What is MDI form? What are the locks available in Visual Basic? Diff type of Datatypes? What is Tabstrip control? What is Static Variable? What is DBSqlPassThrough? What is the starting Index value? How to locate it? What is Parser Bug? What is keyword used to compare to objects? Suppose from form1 to form2 object property settings will arise to ? What is the return type of Instr and Strcmp? What is Implicit? e will we give the option explicit keyword and for what? How can we call Stored procedure of Back End in RDO and ADO ? What is Static Cursor? How to check the condition in Msgbox? What is control array and how many we can have it with in the form? What is diff between the Generic Variable and Specific Variable? What is the diff. Between function and sub procedures? What is the max size allowed for Extension in Visual Basic? What is FireHouse Cursors? With in the form we want to check all the text box control are typed or not? How? What are the type of validation available in VB? How to trap Data Base Error? How to declare Dll Procedure? Referential Integrity (Take care By jet database Engine). Cascade Delete, Cascade Update is done setting property of Attributes.? How to increase the Date corresponding with month,date,year? Name some date function? What is difference between datagrid and flexgrid? What are two validate with Data Control? To connect the Data Control with Back end What are all the properties to be set? What are the Technologies for Accessing Database from Visual Basic?set? What is the diff between the Create Object and Get object? What is Mask Edit and why it is used? What is RdExecDirect? Different type of Passing Value? What are types of binding? What is Dataware Control? What methods are used for DBGrid in unbound mode? What is ADO? What are its objects ? What is the max size allowed for Max Text box length. Record set types and Number available in VB? What is the max size allowed for Max Control Names length? How many procedures are in VB? What is the max size allowed for Max label caption length.? what will be the result for 15/4 and 154 ? What is the max size allowed for Msgbox Prompt and Input Box? Calling Stored Procedures in VB? DSN Less Connection?
The area under which the container provides the view of the ActiveX Document is known as a view port.
Syntax Errors, Runtime , Logic.
Std Global with in the project. Cls Global through out the all project only thing is we want to set the type lib. Class Modules can be Instantiated.
Static + Keyset
State 0 Source control is being dragged with the range of a target.
1 Out of the range of a target.
2 One position in the target to another.
Simple, Dropdown list We can type and select. Dropdown Combo Only Drop Down.
Simple Single Select , Extended. Multiple Select.
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.
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.
Screen.MousePointer = VBHourGlass/VBNormal.
Scope sharable between projects.
Rolls Back updates if any errors Occurs.
RdOpenFowardOnly 0 (Default used only for the read only purpose)
RdOpenStatic 1
RdOpenDynamic 2
RdOpenKeySet 3 (Normally used for the live project)
RDO is Hierarchy model where as ADO is Object model. ADO can access data from both flat files as well as the data bases. I.e., It is encapsulation of DAO, RDO , OLE that is why we call it as OLE-DB Technology.
RdConcurReadOnly 0 (Default)
RdConcurLock 1 (Pessimistic Locking)
RdConcurRowver 2 (Optimistic Lociking)
RdConcurValues 3
RdConcurBatch 4
Public, private, Friend
Properties Public variable of a Class
Method Public procedure of a class
Private cannot be used in front of DIM.
Private Only for the Specific Module.
Public not creatable Private & Public
Multi Use - Variable we have to declare.
Single Use Not possible through dll.
Global Multiuse Have variable not Required to Declare.
Global Single Use - Only for exe.
Predefined, Custom, User Defined.
Only in DbOpenTables.
Syntax: rs.index = "empno"
rs.seek "=" , 10
If with our setting the rs.index then run time error will occur.
Object.Zorder = 1 or 0 Place a Specified mdiform form or control at the front or back of the z-order with n its Graphical Level.
No.
No Properties Available. Only the methods they are SetText, GetText, Setdata(), Getformat(), Clear.
Microsoft ODBC driver will support all the methods and properties of Visual Basic. Where as the Oracle not.
Methods Events
Begin Trans Validate
Commit Trans Reposition
Rollback Trans Error
Cancel Query Complied
Refresh
Update Controls
Update row
Messaging Application programming Interface.
MDI Styles
Locking is the process by which a DBMS restricts access to a row in a multi-user environment 4 types of locks. They are
1. Batch Optimistic
2. Optimistic
3. Pessimistic
4. ReadOnly
Operations in a relational database act on a complete set of rows. The set of rows returned by a SELECT statement consists of all the rows that satisfy the conditions in the WHERE clause of the statement. This complete set of rows returned by the statement is known as the result set.
Applications, especially those that are interactive and online, cannot always work effectively with the entire result set as a unit.
These applications need a mechanism to work with one row or a small block of rows at a time. Cursors are an extension to result sets that provide that mechanism.
Cursor or lock type Advantages Disadvantages AdOpenForwardOnly (Default) Low resource requirements Cannot scroll backward No data concurrency AdOpenStatic Scrollable (Wont detect changes made at the same time by another application) No data concurrency AdOpenKeyset Some data concurrency Scrollable Higher resource requirements Not available in disconnected scenario AdOpenDynamic High data concurrency Scrollable Highest resource requirements Not available in disconnected scenario AdLockReadOnly Low resource requirements Highly scalable Data not updatable through cursor AdLockBatchOptimistic Batch updates Allows disconnected scenarios Other users able to access data Data can be changed by multiple users at once AdLockPessimistic Data cannot be changed by other users while locked Prevents other users from accessing data while locked AdLockOptimistic Other users able to access data Data can be changed by multiple users at once
LOB (Large Object Data type).
CLOB (Stores Character Objects).
BLOB ( Store Binary Objects such as Graphic, Video Chips and Sound files).
BFILE(Store file pointers to LOB It may Contain filename for photo’s store on CD_ROM).
Libraries of procedure external to the application but can be called from the application.
Its Scope will be available through out the life time.
It will By Passing the Jet Query Processor.
It is tab control to place our controls with in the form in multiple sheets.
Index starts with 1.
And to identify If Tabstrip1.SelectedItem.
Index = 1 Then ..
End if
It is difficult to use database objects declared in a module from within a form.
ISOperator Returns Boolean.
Invalid procedure call or argument (Run time error 5)
Instr integer (Numeric position)
Strcmp - integer ( if both the string are equal they result = 0)
Strcmp (Str1, Str2, Comparetype)
Comparing mode = 0 Binary Comparing
1 Textual Comparing
Instance of specific copy of a class with its own settings for the properties defined in that class.
Note: The implicitly defined variable is never equal to nothing.
In the general declarations section. To trap undeclared variables.
In RDO We can call using RDO Query Objects.
In ADO We can call using Command Objects.
In ADO Snap Shot is called so.
If(Msgbox("Do you want to delete this Record",VbYesNo)=VbYes)Then End if
Group of control share the same name. Max 32, 767.
Generic Variable:
Create Object Ex:-Ole-Automation . No need refer the object library.
Specific Variable:
Binding Procedure Early and Late Binding ( Can be Remove from the Memory).
Function will return value but a sub procedure wont return values
Frm, bas, cls, res, vbx, ocx, frx, vbp, exe
Forward Only Some time Updateable
For each currentcontrol in controls
if typeof currentcontrol is TextBox then
end if
next
Field, Form
Dim x as RDOError
X(0).Des
X(1).Number
Setting the Cursors.
Default Cursor 0
ODBC Cursor (Client side) 1
ServerSide Cursors (More Network traffic) - 2
Declare function "" lib ""
Alias "" (Arg, ..) as Return type.
DbRelationDeleteCascade, DbRelationUpdateCascade.
DateSerial(year(Now),Month(Now)+1,1)
Hour, min, sec, month, year, DateSerial, dateadd, datediff, weekday, datevalue, timeserial,timevalue.
Dateadd(), Datediff(), Datepart(), Cdate()
Datagrid Editable. Flexigrid Non-Editable. (Generally used for Read only purpose.)
Data_Validate, Data_Error.
Data source Name, Record Source Name
DAO, Data Control, RDO, ODBCDIRECT, ADO, ODBC API , 0040.
Create Object - To create an instance of an object.
Get Object To get the reference to an existing object.
Control. Restricted data input as well as formatted data output.
Bypasses the Creation of a stored procedure to execute the query. Does not apply to Oracle.
By value, By ref, Optional, Param Array. Note:- Optional keyword cannot be used while declaring arguments for a function using param array.
Assigning variable with defined memory space.
Late Binding - Memory size is allotted in later stage.
Ex:- Dim x as object
Early Binding - Memory size is allotted while declaring itself. New Key word is important.
Ex:- Dim x as New Object
Any control bound to Data Control.
Ex:- Textbox, Check Box, Picture Box, Image Control, Label, List box, Combo Box, DB Combo,
AddData, EditData, Readdata, WriteData.
ActiveX Data Object. ADO can access data from both flat files as well as the databases. I.e., It is encapsulation of DAO, RDO, and OLE that is why we call it as OLE-DB Technology. Objects are Connection, Record Set, Command, Parameter, field, Error, Property.
32,000
3.
1- Dynaset, 0 Table, 2 Snap Shot.
255.
2.
function and sub procedures
2,048
15/4 = 3.75 and 154 = 3
1024
1. Calling Simply the Procedure with out Arguments "Call ProcedureName}"
2. If it is with Arguments Means then
Declare the Query Def qy
Set Qy as New Query def
Qy.SQL = "{Call ProcedureName(?
"Server=Oracle; Driver={Microsoft ODBC for Oracle};"
Visual Basic Interview Continue...
Labels: VB Technical
Visual Basic Interview Questions and Answers
How do you register a component? Name and explain the different compatibility types when creating a COM component Why is it important to use source control software for source code? What two methods are called from the ObjectContext object to inform MTS that the transaction was successful or unsuccessful? What is the tool used to configure the port range and protocols for DCOM communications? What does Option Explicit refer to? 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 Name the four different cursor types in ADO and describe them briefly. Name the four different locking type in ADO and describe them briefly. Describe Database Connection pooling (relative to MTS )? What are the ADO objects? Under the ADO Command Object, what collection is responsible for input to stored procedures? What are some benefits of using MTS? What is the benefit of wrapping database calls into MTS transactions? Describe and In Process vs. Out of Process component. Which is faster? What are the main components of the ADO object model? How are they used? Can We create CGI scripts in VB?? Dim x, y as integer. What is x and y data type? What is Centralization Error Handling? What is frx? What is the Dll required for running the VB? Why we use Treeview Control? Handling Error in Calling chain. In project properties if we set Unattended what is it mean? What is the size of the variant data type?
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.
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.
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.
Labels: VB Technical
