What Is a Control File?Every Oracle Database has acontrol file, which is a small binary file that records the physical structure of the database. The control file includes: The database name Names and locations of associated datafiles and redo log files The timestamp of the database creation The current log sequence number Checkpoint informationThe control file must be available for writing by the Oracle Database server whenever the database is open. Without the control file, the database cannot be mounted and recovery is difficult.The control file of an Oracle Database is created at the same time as the database. By default, at least one copy of the control file is created during database creation. On some operating systems the default is to create multiple copies. You should create two or more copies of the control file during database creation. You can also create control files later, if you lose control files or want to change particular settings in the control files.

2 What is activer explain difference between activer exe and dll A standard exe application is one that is created usingStandard EXE project. It is the most widely used Projecttype using VB6. Standard EXE application is normally themost widely used among the available Project types in VisualBasic. Stand-alone programs have an .EXE file extension.

UsageA standard EXE application is normally used when you want todevelop a stand-alone application. Examples includecalculators, text editors, and other similar applications.

An ActiveX EXE application is one that is created usingActiveX EXE project. ActiveX EXE are widely used inconjunction with standard EXE applications. There are threetypes of widely used of ActiveX projects. These are:

a. ActiveX EXE

b. ActiveX DLL

c. ActiveX Control

ActiveX EXE: Unlike a stand-alone EXE file, an ActiveX EXEfile is designed to work as an OLE server, which is nothingmore than a program designed to share information withanother program. It has an .EXE file extension.

ActiveX DLL: ActiveX DLL files are not meant to be used bythemselves. Instead, these types of files containsubprograms designed to function as building blocks whencreating a stand-alone program. It has a .DLL file extension.

ActiveX Control: Unlike an ActiveX DLL or ActiveX EXE file,an ActiveX Control file usually provides both subprogramsand a user interface that you can reuse in other programs.It has an .OCX file extension.

Usage1. The ActiveX EXE/DLL is normally used when you need tobuild a component that is separate from the main program.The concept is based on COM model.

2. ActiveX DLL/EXE allows multiple applications to share thesame code. This allows for scalability of programs, andsaves time because you only need to write the code once.

3. ActiveX DLLs and ActiveX EXEs are almost same in the waysthey are built and used. In either case, you build one ormore classes that applications can use to do something.

4. One of the main differences between ActiveX EXE and anActiveX DLL's is that the code is executed within the mainprogram's address space for ActiveX DLL. This is because thecode lies inside the program's address space, callingmethods and execution of code is very fast.

Differences

An ActiveX Exe provides the reusability of code, byaccessing it from different clients.

An ActiveX Exe is a component that can be called by anotherapplication by providing a reference to the component. But aStandard Exe application cannot be called in this way.

An ActiveX EXE's code is run in a separate process. When themain program calls an ActiveX EXE's method, the applicationpasses required parameters into the ActiveX EXE's and callsthe method. The ActiveX EXE, upon execution may return theresults to the main program. This is slower than running anActiveX DLL's method inside the main program's address space3 write advantages of active hdl over active hehe Components provide reusable code in the form of objects. An application that uses a components code, by creating objects and calling their properties and methods, is referred to as aclient.Components can run either in-process or out-of-process with respect to the clients that use their objects. An in-process component, or ActiveX DLL, runs in another applications process. The client may be the application itself, or another in-process component that the application is using.Figure 2.1In-process components are used by applications or other in-process components

The series of step-by-step procedures in this chapter builds an in-process component called ThingDemo, with class modules that demonstrate object lifetime, global objects, and objects that control modal and modeless dialog boxes.Youll also see how to debug an ActiveX DLL in process, by running the DLL and a test project together in the Microsoft Visual Basic development environment.The procedures for creating the ThingDemo component build on each other. The sequence in which you perform the procedures is therefore important.

4 WHAT IS ODBC ? HOW WE CAN CREATE DSN?WebAccess uses an ODBC connection to SQL Server. ODBC is an acronym for Open Database Connection. DSN is an acronym for Data Source Name.The Microsoft SQL Server ODBC Device Drivers must be installed on the Project Node.There are two SQL ODBC drivers that appear to work with SQL Server 2005:1) theSQL Native ClientDriver installed as part of the SQL Server 2005 client services. Use this driver is the Project Node and the SQL Server 2005 are the same PC or if you installed the SQL Server 2005 client services on the WebAccess Project Node.2) TheSQL ServerDriver part of Windows XP Professional and Windows 2000 dated 10/28/2003 and later (version 3.70.11.46 of SQLSRV32.DLL). Use this if the SQL Server is on a remote node.It is easier to use a System DSN. The System DSN allows access to the SQL ODBC drivers no matter who is logged on to the Project Node. The System DSN also makes for less confusion later on.A User DSN will work as well. The User DSN is specific to each user and allows you to restrict which users have access. However, you must configure a User DSN for each user that might be logged on the Project Node.Any name can be given to the DSN. But make it one that you can remember This DSN name must be entered into the WebAccess Project Manger as the ODBC Log Data Source.Configure "Native Client SQL Server" DSN1.From Control Panel open ODBC Data Source Administrator, on the Project Node.Start -> Control Panel -> Administrative Tools -> Data Sources (ODBC).

2.SelectSystem DSN.

3.Click on theADDbutton. This will open theCreate New Data Sourcedialog box, shown below.

4.Look for the driver titledSQL Native Client. If this driver is not listed in the window and the SQL Server is, go to Section2. Configure SQL Server DSN.5.Double-click on the driverSQL Native Client. The Create a New Data Source to SQL Server Setup dialog box will open, as shown below.

6.In theNametext box, enter a name for this DSN. You will have to enter this name in WebAccess Project Node.For example, bwSQLData7.In theServercombo-box, you must enter the name of the computer running SQL server.

If SQL Server is installed on the Project Node, Select (local).Otherwise, select the computer with the SQL Server. (Note - if you do not see the other computer listed, you should try to Register SQL server as described earlier).8.Click on theNext >button.9.Select "SQL Server authentication". Enter thesaas the user login ID and thepasswordyou created instep 14 of Section 23.3.1 Install SQL Server 2005.

Figure 23.3 Use SQL Server Authentication and SQL Server login ID and Password.Select Next after you have entered the password for the sa account. (or whatever account you know will work).10.ChecktheChange the default database to.Use the Pull Down box or type the Database name you created in SQL Server Management Studio. This name has to match exactly. Go back to Section23.3.2 Create and SQL Server Databaseif you skipped this step or forgot theDatabase name. In the example it was WebAccessPData.

SelectNext.11.Check "Use regional settings.....".

12.SelectTest Data Source.

13.You should see "TESTS COMPLETED SUCCESSFULLY!". Select OK.

If it did not Test Successfully. Try these steps:If the SQL Server is a remote node, verify that TCP port 1433 is open on the SQL Server Node (i.e. check any firewalls or Windows Firewall).Verify the SA Login Password or whatever Login ID you used to configure this DSN.Verify the Database name.Verify that SQL Server is running.14. SelectOKthree times (one for each dialog box) to exit ODBC configuration.15.You should remember the DSN name, because this is what you will tell WebAccess to use. In this example the ODBC DSN isbwSQLData. It could have been any name that you used, just remember it.

16. Next and last step is to tell WebAccess to use the DSN. See Section20.8.1 Create an ODBC Log Data Source. and20.8.2 Select new ODBC Log Data Source. And be sure to Select the ODBC Data source

5 EXPLAIN DAO , RDO AND ADO WHAT OLE EXPLAIN ?ADO, DAO and RDO in Visual BasicIn Visual Basic, three data access interfaces are available to you: ActiveX Data Objects (ADO), Remote Data Objects (RDO), and Data Access Objects (DAO). A data access interface is an object model that represents various facets of accessing data. Using Visual Basic, you can programmatically control the connection, statement builders, and returned data for use in any application.Why are there three data access interfaces in Visual Basic? Data access technology is constantly evolving, and each of the three interfaces represent a different state of the art. The latest is ADO, which features a simpler yet more flexible object model than either RDO or DAO. For new projects, you should use ADO as your data access interface.Why Use ADO?ADO is designed as an easy-to-use application level interface to Microsoft's newest and most powerful data access paradigm, OLE DB. OLE DB provides high-performance access to any data source, including relational and non-relational databases, email and file systems, text and graphics, custom business objects, and more. ADO is implemented for minimal network traffic in key Internet scenarios, and a minimal number of layers between the front-end and data source all to provide a lightweight, high-performance interface. ADO is called using a familiar metaphor the OLE Automation interface. And ADO uses conventions and features similar to DAO and RDO, with simplified semantics that make it easy to learn.

6 WRITE DIFFERENCE BETWEEN ODBC AND OLEDB?Both are specifications which describe how an application program can access the data in a data store. ODBC stands for Open Database Connectivity. The ODBC call-level interface specification was created by Microsoft in 1992 as a way to standardize program-to-SQL data communication. Before ODBC, application programmers had to use a different set of API calls for every type of database. By creating a standard interface, programmers could write one set of code (for the most part) that would work with any ODBC-compliant database. ODBC was quickly embraced by most major database vendors and became a de facto standard. Notice that this cooperation happened when Microsoft was not a very large company.OLE DB originally stood for Object Linking and Embedding for Databases, but now the acronym just means a COM-based interface to a wide range of data sources. OLE DB is sometimes written as OLEDB or OLE-DB. OLE DB came into being in the mid 1990s through an evolution and merging of several Microsoft technologies. The idea of OLE DB is to provide programmers with a consistent interface to many different types of data, including SQL databases, Excel spreadsheets, and so on.The best way to understand the relationship between ODBC and OLE DB is by way of a picture. (Click on the image at the bottom of this blog entry to enlarge it so you can see it clearly). Imagine that you are a developer or tester writing a program which needs to access and manipulate some data. If the data is stored in a SQL relational database, use can use ODBC calls. It turns out that working directly with ODBC is a bit awkward. An alternative is to use OLE DB. OLE DB programming tends to be quite a bit easier than ODBC programming, in part because OLE DB operates at a higher level of abstraction. The downside of OLE DB is a slight performance penalty in most cases. Now if you want to get at Excel data, you can also use OLE DB calls to access and manipulate the data. Of course Ive left out a lot of details, but this overview should help you understand the difference between ODBC and OLE DB.

7 what do you mean by sql explain ddl dml dcl in detail

DDL

Data Definition Language(DDL) statements are used to define the database structure or schema. Some examples: CREATE - to create objects in the database ALTER - alters the structure of the database DROP - delete objects from the database TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed COMMENT - add comments to the data dictionary RENAME - rename an objectDML

Data Manipulation Language(DML) statements are used for managing data within schema objects. Some examples: SELECT - retrieve data from the a database INSERT - insert data into a table UPDATE - updates existing data within a table DELETE - deletes all records from a table, the space for the records remain MERGE - UPSERT operation (insert or update) CALL - call a PL/SQL or Java subprogram EXPLAIN PLAN - explain access path to data LOCK TABLE - control concurrencyDCL

Data Control Language(DCL) statements. Some examples: GRANT - gives user's access privileges to database REVOKE - withdraw access privileges given with the GRANT commandTCL

Transaction Control(TCL) statements are used to manage the changes made by DML statements. It allows statements to be grouped together into logical transactions. COMMIT - save work done SAVEPOINT - identify a point in a transaction to which you can later roll back ROLLBACK - restore database to original since the last COMMIT SET TRANSACTION - Change transaction options like isolation level and what rollback segment to use SQLupDifference between TRUNCATE, DELETE and DROP commands Loginto post commentsSubmitted by madhuker (not verified) on Wed, 2005-04-06 03:20.DML statements can be rollbacked where DDL are autocommit. Loginto post commentsDML commands can't beSubmitted by ramakrishna (not verified) on Thu, 2006-01-05 09:35.DML commands can't be rollback when a DDL command is executed immediately after a DML. DDL after DML means "auto commit". The changes will return on disk not on the buffer. If the changes return on the buffer it is possible to rollback not from the disk. Loginto post commentsSubmitted by R. SATISH KUMAR (not verified) on Wed, 2005-04-13 03:09.DEAR SIR,Let me tell you the difference between DDL,DML,TCL and DCL:DDL COMMANDS:CREATE,ALTER,DROP AND TRUNCATE ARE CALLED DDL COMMANDS. They are called Data Definition since they are used for defining the data. That is the structure of the data is known through these DDL commands.DML COMMANDS:DML commands are used for data manipulation. Some of the DML commandsinsert,select,update,delete etc. Even though select is not exactly a DML language command oracle still recommends you to consider SELECT as an DML command.TCL:For revoking the transactions and to make the data commit to the database we use TCL. Some of the TCL commands are:1. ROLLBACK2. COMMITROLLBACK is used for revoking the transactions until last commit.COMMIT is used for commiting the transactions to the database.Once we commit we cannot rollback. Once we rollback we cannot commit.Commit and Rollback are generally used to commit or revoke the transactions that are with regard to DML commands.DCL:Data Control Language is used for the control of data. That is a user can access any data based on the priveleges given to him. This is done through DATA CONTROL LANGUAGE. Some of the DCL Commands are:1. GRANT2. REVOKE."THESE ARE REFERRED FROM THE BOOK 'ORACLE 9i complete Reference' written by Kooch and George. This is an Oracle Press Release." If you want further details about this topic I can give you. Since I don't know your e-mail address I am not able to send you the complete information. I will give my e-mail address. That is,satish_sathya1983@yahoo.co.in. You can send your email address to my email and i will discuss about this topic with you. If you can send me your email address I can send you an complete attachment of this topic.