NOT NULL constraints in Microsoft SQL Server allow you to specify that a column may not contain NULL values. When you create a new NOT NULL constraint on a database column, SQL Server checks the column's current contents for any NULL values. If the column currently contains NULL values, the constraint creation fails. Otherwise, SQL Server adds the NOT NULL constraint and any future INSERT or UPDATE commands that would cause the existence of a NULL value fail.

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In a recent forum message, Redwings2010 wrote:

"My boss wants me to create a form using Access 2007 that would open a specific PDF file to view in the form. He doesn't want to click on and view the PDF file outside Access. Is that possible?"

Can you help? Interested in solutions to the same problem? Visit the About Databases forum and join the discussion!

The transaction log plays a critical role in a SQL Server database: it maintains an ongoing record of database activity crucial for the restoration of recent data in the event of a disaster. However, this benefit comes at a cost: the transaction log can consume a substantial amount of space in an active database. SQL Server provides two actions designed to counterbalance these large space requirements: transaction log truncation and log file shrinking.

Read more in SQL Server Transaction Log Management

The Oracle Certified Database Administrator (OCA) credential is an entry-level certification designed to serve as a stepping-stone to the more advanced Oracle Certified Professional (OCP) and Oracle Certified Master (OCM) programs. Currently, there are three active certification programs: Oracle 9i, Oracle 10g and Oracle 11g. I'd strongly encourage you to certify on the most recent version of Oracle in order to maintain your credential as long as possible.

Read the full story: Oracle Certified Associate