Use TryGet pattern for transient values

A number of objects may have extra properties or something where it might not exist for all instances. A good example might be finding Controlsource property on an Access.Control variable:

Not all controls have a ControlSource property and thus can fail to run. A common approach is to use OERN:

This will work…

Self-documenting code

Strong preference should be given to writing code that is self-documenting. A common approach is to write a lot of comments, but the problem with comments are twofold: It actually can harm the readability because it adds to the overall length of code to read and understand. It must be correct or it can end…

MODULE LEVEL VARIABLES

Module level variables

It is common to create a big wall of declaration in a module such as this:

While the code will compile and work fine, the discoverability and naming of the module level variables does become difficult and unwieldy. To help cut down on this ambiguity, it is recommended to create a private user-defined type…

Prefer compile time errors over run time errors

In VBA, there are several features that allow us to do things that may not be checked at the compile time. In particular, it is possible to write several late-bound expressions which means that it can potentially contain run-time errors. One common misconception about late-binding is that it’s a matter of adding a reference and…

Truthy and Falsy Values

“Truthy” and “Falsy” Values

VBA is quite very loose in what it deems “truthy” and “falsy”. For example, this procedure can produce surprising result:

At the first glance, it seems expected that if the bit field is set to 1, it would succeed. But in fact, it wouldn’t because True is equivalent to -1, not 1. Unless we…

Normalize all constraints’ & indices’ names

Constraints that are created by SSMA or by user via SSMS tend to have ugly names. Worse, auto-generated names are not stable across backups. Meaning if you restore a new database based on a copy of another database, the constraint names will change. That create huge problems during migrations because scripts that references constraint will…

Pivoting a dynamic set

SQL Server does not allow for a dynamic set, which can be problematic if you need to pivot based on the data that comes from rows and you can have various values in the column. In general, you need a stored procedure and dynamic SQL in order to handle the dynamic pivots. This requires uses…

Using Custom Functions in Calculated Controls

Custom functions work the same way as MS Access built-in functions such as DateAdd, DatePart and DSum, but are instead created ourselves as database developers.  We do this by creating a public function with the VBA programming language and save it inside a global module within the database. Today I am going to explain how custom functions can be…

Enable and Disable a Form Control using VBA

I was working on a design for an Order Management Database, and one of the tasks I dealt with involved dynamically Enabling or Disabling one of the form’s Command Buttons’ using VBA. This gave me the idea for the present Access tip. The command button was located on a Customer Details form which had an Orders…