Here is a question that you can use to assess the skills of a junior level VB developer. A developer with 6 months Visual Basic 6 experience should understand this question and be able to explain the correct answer. This question will test the applicant's basic understanding of ADO (Active Data objects), which is the technology Microsoft recommends for accessing data sources. Anyone who has built a 'production' visual basic application should be able to answer this question.

When using ADO in a Visual Basic 6.0 Application, what are the 3 main objects for ADO? Describe each object and it's purpose.

The three main objects are the Command, Connection, Recordset objects.

The candidate should be able to explain the following points:

• The Connection object is the top object in the hierarchy. The other objects use this object to connect to the database. A connection object will connect to 1 database.
  
  
• The Command object is used to execute stored procedures and SQL.
  
  
• The Recordset object is used to store records returned from a database. It can be thought of as a container for the resultset returned from a database query.

If the candidate talks about DAO (data access objects) or RDO remote data objects these are older technologies; it could mean the candidate is not as experienced with ADO.

The Parameter, Field, Error, and Property objects are 'minor' objects used in ADO, if a candidate gives these answers it may show that he or she has only read about but not used the technology. While these 'minor" objects are technically objects used in ADO, they are not as common as the command, connection and Recordset objects.

A candidate may state that a 'clone' is one of the main objects. A clone is a method, not an object. This answer would imply that the candidate is not experienced in using ADO but might have some minimal exposure. Other incorrect answers are begintrans, committrans, rollbacktrans and execute which are also methods not objects.

Follow- up questions:

How can you tell if a Recordset Object contains no records?

Check to see if the .bof property and .eof property are both true. The candidate may offer the count property, or recordcount property, these are both incorrect.

How do you specify which database you are connecting to?

The connection object is configured with a connectionstring, which provides information to the connection object such as the database it's going to connect to login, password, etc.

What are some of the methods used to move through a Recordset object?

About the author

Mark Horninger, A+, MCSE+I, MCSE, MCSD, MCDBA, is President and founder of Haverford Consultants Inc. (http://www.haverford-consultants.com), located in the suburbs of Philadelphia, PA. He develops custom applications and system engineering solutions, specializing primarily in Microsoft operating systems and Microsoft BackOffice products. He has over 12 years of computer consulting experience and has passed 31 Microsoft Certification Exams. During his career Mark has worked on many extensive and diverse projects including database development, client server and web-based application development, training, embedded systems development and Windows NT and 2000 project rollout planning and implementations. Mark is a contributing author to the books: MCSE Windows 2000 Professional Study Guide, Designing SQL Server 2000 Databases for .NET Enterprise Servers, VB .NET Developers Guide and Configuring and Troubleshooting Windows XP Professional.

Mark lives with his wife Debbie and three children in Havertown, Pa. and can be reached at mark@haverford-consultants.com or markh@op.net.