May 13, 2000

Unrecognized Database Format Error Message with Access 2000 Databases

The standard DAO Data control is designed to work with the Jet 3.5 Engine, whereas Access 2000 database can be accessed only by the more recent Jet 3.6 engine. For this reason, any attempt to access an Access 2000 database using the standard DAO Data control, as well as regular

Don’t use = operator on Date values

Date variables store values in floating point format, much like Double variables, with the integer part for dates and the fractional part for the time portion. Being floating point values, Data values may be subject to rounding problems, and for this reason you shouldn’t test two Date variables for equality

Use Server.HTMLEncode for strings stored in a database

If your ASP pages display strings stored in database fields, you should always process the strings with the Server.HTMLEncode method, otherwise the string won’t be displayed correctly in the user’s browser if it contains characters that have a special meaning to HTML, such as the quote (“), the less-than ()

Logging under a different name makes your add-ins disappear

After you install Visual Basic and log on to the machine as a different user (with or without administrator privileges), you cannot see any Add-Ins in the Add-In dialog in Visual Basic. I ran across this problem when I logged in and installed VB6 on NT Workstation under my User,

Out-of-date dependency file for COMCTL32.OCX

Have you ever read a message like “Dependency file for COMCTL32.OCX is out of date” during the package creation process? The cause of this problem is simple: you have installed an application that has replaced your COMCTL32.OCX ActiveX with the newer release (which is 5.00.3828 at this time). The ActiveX

References to form and controls prevent complete form unloading

When you assign a reference to a form (or one of its controls) to an object variable which is stored outside the form module, you must set the variable to Nothing or the form won’t be completely unloaded. In other words, it will become invisible but will continue to take

ASP components aren’t released by setting their references to Nothing

If you instantiate an ActiveX component from an ASP script under IIS 4 and previous versions, using the Server.CreateObject command, you might believe that the object is deallocated as soon as you set its reference to Nothing – this is how all COM components work, right? The problem with ASP

Null values in WHERE clauses

A SELECT query returns all the rows for which the WHERE clause returns True. However, many developer – especially those accustomed to other programming languages, such as VB – get confused on this point, and assume that the query returns the rows for which the WHERE clause returns any non-False

GROUP BY and UNION may return unsorted resultsets

In SQL Server 6.5 and previous versions, the GROUP BY clause in a SELECT statement was carried out by temporarily sorting the resultset before grouping similar rows, therefore the end result was always sorted. For this reasons, many programmers omitted the ORDER BY clause, because the result was sorted anywaySQL