Tutorial: Undocumented SysCmd Functions. Convert to MDE programmatically, compact database programmatically, get Access Process ID. VBA UserForms: Fill a Combo Box or List Box List from a Database. There are different ways to create the list of items displayed by a combo box or a list box on a VBA. Microsoft Access is a development environment used to create computer-based databases. To complement it, it ships with a programming language. A database is a list of values stored somewhere. A computer database is a list or a group of lists stored in a computer disc such as a hard drive.
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VBA Objects - The Ultimate Guide“High aims form high characters, and great objects bring out great minds” – Tryon Edwards. A Quick Guide to VBA Objects. Task. Examples. Declare and Create. Dim coll As New Collection Dim o As New Class.
Declare Only. Dim coll As Collection Dim o As Class. Create at run time. Set coll = New Collection Set o = New Class. Assign to Excel Object.
Dim wk As Workbook Set wk = Workbooks(. Using objects is not that difficult. In fact, they make your life much easier.
In this post, you will see how VBA makes brilliant use of objects. How objects such as Collections, Workbooks and Worksheets save you much complexity, time and effort. In my next post, I will cover creating objects using Class Modules. However, before you create your own it is vital that you understand exactly what they are and why you need them. So grab your favourite beverage and take a journey into the fascinating world of VBA objects. What is a VBA Object? To understand what an object is, we must first look at simple variables.
In VBA we have basic data types such as string, integers, double and date. To store a value while our application is running.
We either put a value in the variable or read a value from the variable. Dim Marks As. Long' Store value in Marks.
Tutorial: ADO Programming Code Examples, demonstrating how to use the ADO library to list and manipulate the objects in Access.
Marks = 3. 4 + 4. Marks = Range(. The following code shows an example of using a Collection in VBASub Use. Collection(). Dim coll. Fruit As. New Collection.
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Access VBA functions to list all tables, queries, forms and reports in Microsoft Access database: functions list each table, query, form or report object in current.
Add item to the collection. Fruit. Add . It is more than a variable. That is, it does more than storing a piece of data. We can add items, remove items and get the number of items. Definition of a VBA Object: An object is a grouping of data and procedures(i. Functions and Subs). The procedures are used to perform some task related to the data.
In the Collection the data is the group of the items it stores. The procedures such as Add, Remove, Count then act on this data. In the Worksheet object, the main data item is the worksheet and all the procedures perform actions related to the worksheet. Why VBA Uses Objects. An object is used to represent real world or computer based items.
The major benefit of an object is that it hides the implementation details. Take the VBA Collection we looked at above.
It is doing some complicated stuff. When an item is added it must allocate memory, add the item, update the item count and so on. We don’t know how it is doing this and we don’t need to know. All that we need to know is when we use Add it will add the item, Remove will remove the item and Count will give the number of items. Using objects allows us to build our applications as blocks.
Building it this way means you can work on one part without affecting other parts of your application. It also makes it easier to add items to an application. For example, a Collection can be added to any VBA application.
It is not affected in any way by the existing code and in turn it will not affect the existing code. A Real World Analogy. Looking at a real- world example can often be a good way to understand concepts.
Take a car with a combustion engine. When you are driving your car, a lot of complex stuff is happening. For example, fuel gets injected, compressed and ignited leading to combustion. This then causes the wheels of your car to turn. A nice looking combustion engine . All you expect is that turning the key will start the car, pressing the accelerator will speed it up and pressing the brake will slow it down and so on. Think of how great your code would be if it was full of these type of objects.
Self- contained and dedicated to performing one set of tasks really well. It would make building your applications so much easier. Object Components. There are three main items that an object can have. These are. Properties – These are used to set or retrieve a value. Methods – These are function or subs that perform some task on the objects data. Events – These are function or subs that are triggered when a given event occurs If you look in the Object Browser(F2) or use Intellisense you will notice different icons beside the members of an object.
For example, the screenshot below shows the first three members of the Worksheet object What these icons mean is as follows Let’s take a look at the first three members of the worksheet. It has an Activate method which we can use to make worksheet active. It has an Activate event which is triggered when the worksheet is activated.
The Application property allows us to reference the application(i. We read and write to a property the same way we read and write to a variable.' Set the name. Name = . For example, the Worksheet has a Used.
Range property that return a Range object. Set rg = Sheet. 1. Used. Range. You will notice we used the Set keyword here. We will be looking at this in detail later in the post.
Object Methods. A method is a Sub or a Function. For example, Add is a method of the Collection' Collection Add method.
Coll. Add . With a Collection, the main data is the group of items we are storing. You can see that the Add, Remove and Count methods all perform some action relating to this data. Another example of a method is the Workbook Save.
As method. Dim wk As Workbook. Set wk = Workbooks. Open . What this means is that the code runs when an event occurs.
Common events are button clicks, workbook Open, worksheet Activate etc. In the code below we display a message each time Sheet. This code must be placed in the worksheet module of Sheet. Private. Sub Worksheet. We create an object using the New keyword. If we try to use an object before it is created we will get an error.
For example, take a look at the code below. Dim coll As Collection. Add . We can perform these steps in one line using Dim and New together. Alternatively, we can declare the variable in one line and then create and assign the object in another line using Set. Let’s take a look at both of these techniques. Using Dim with New.
When we use Dim and New together they declare, create and assign all in one line.' Declare, Create and Assign. Dim coll As. New Collection. Using code like does not provide much flexibility. It will always create exactly one Collection when we run our code. In the next section we will look at Set. This allows us to create objects based on conditions and without having to declare a variable for each new object. Using Set with New.
We can declare an object variable in one line and then we can use Set to create and assign the object on another line. This provides us with a lot of flexibility. In the code below we declare the object variable using Dim. We then create and assign it using the Set keyword.' Declare. Dim coll As Collection. Create and Assign.
Set coll = New Collection. We use Set in this way when the number of objects can vary. Using Set allows us to create multiple objects. In other words, we can create objects as we need them. We can’t do this using Dim and New. We can also use conditions to determine if we need to create an object e.
Dim coll As Collection. Only create collection if cell has data. If Range(. Subtle Differences of Dim Versus Set There are some subtle differences between using New with Set and using New with Dim. When we use New with Dim, VBA does not create the object until the first time we use it. In the following code, the collection will not be created until we reach the line that adds “Pear”. Dim coll As. New Collection. Collection is created on this line.
Add . A Dim statement is different to other VBA lines of code. When VBA reaches a Sub/Function it looks at the Dim statements first. It allocates memory based on the items in the Dim statements.
It is not in a position to run any code at this point. Creating an object requires more than just allocating memory. It can involve code being executed. So VBA must wait until the code in the Sub is running before it can create the object.
Using Set with New is different in this regard to using Dim with New. The Set line is used by VBA when the code is running so VBA creates the object as soon as we use Set and New e. Dim coll As Collection. Collection is created on this line.
Set coll = New Collection. Add . If we set the object variable to Nothing and then use it again, VBA will automatically create a new object e.
Sub Empty. Coll. 2(). Create collection and add items. Dim coll As. New Collection. Add . It also creates the worksheet object for each worksheet in the workbook. Conversely, when we close the workbook VBA will automatically delete the VBA objects associated with it. This is great news. VBA is doing all the work for us.
So when we use Workbooks. Open, VBA opens the file and creates the workbook object for the workbook. An important point to remember is that there is only one object for each workbook. If you use different variables to reference the workbook they are all referring to the same object e. Dim wk. 1 As Workbook.
Set wk. 1 = Workbooks. Open(. These include the Dictionary, Database objects, Outlook VBA objects, Word VBA objects and so on. These are written using COM interfaces. The beauty of COM is that was can easily use these libraries in our projects.
If we add a reference to the library we create the object in the normal way.' Select Tools- > References and place a check ' beside . However, it is important to understand what it is used for. When I use “object variable” I mean any variable that isn’t a basic variable such as a string, long or double etc.' wk is the object variable. Dim wk As Worksheet.
Set wk = This. Workbook. Worksheets(1). ' coll. Dim coll. 1 As. New Collection. Add . If we forget to use Set we will get the error below. It may look like Let and Set are doing the same thing.
But they are actually doing different things: Let stores a value. Set stores an address To understand more about this we need to take a peek(pun intended: -)) into memory.
VBA Objects in Memory“Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it” – Alan Perlis To understand what New and Set are doing we need to understand how variables are represented in memory.
Microsoft Access VBA References to Forms and Controlsby FMS Development Team. The cornerstone of any Microsoft Access application is the form. As an Access user and. This article outlines the methods. Access. Although they have big names, they are. Access has several pre- defined objects that.
These are called System Objects. The. Forms system object contains all the forms that are currently open. The. Reports system object contains all the reports that are currently open.
This tells. Access that you are referring to a form, or a control on a form. A good. analogy is the Access Database Container. This is the window that. Access. It contains all the objects in your. You click on the desired object type and a list of available.
The Database Container contains each object in your. System objects are similar in that they contain objects, but. They are virtual containers that only exist in memory. System objects allow you to refer to an object that may have the same name as an object of a. For example, if you have a form and report that are both.
If you prefaced your. Forms system object, Access knows you are talking about. Invoice form. By prefacing the same reference with the Reports. Access knows you are talking about the Invoice report.
Another useful system object is called . This object, used in conjunction with the. Active. Form and Active. Control properties, allows you to refer to the form. Identifier Operators are the shorthand of object oriented systems. These are the ! These operators.
You use the ! You use the . Generally, you'd like to. The bang operator ! However, this is not. Access will always run your application faster if.
This is especially. Access Basic programs. You can also use the dot operator in.
SQL statements. Naming Conventions. When you create objects in Access, it is generally a good idea to use some form of. Give your object names a prefix that symbolizes the. For example, forms should be named . Give controls the . Using. naming conventions will make it easier for your maintain your. The Leszynski/Reddick naming convention is the currently accepted standard for Microsoft.
Access. While still in formative stages, it provides useful rules for. In the examples in this article, I will use an extension of this standard. Object Type. Prefix. Example. Tabletbltbl. Invoice Formfrmfrm. Customer Subformsubfrmsubfrm. Orders Controlctlctl.
Last. Name Reportrptrpt. Past. Due Macromcrmcr. Auto. Exec Modulemodmod. Utilities Refers to the Comments field in the table the form is based on (this assumes that you.
If you had a control named. Comments, this expression would refer to the Comments control, not the. Comments field. Control names take precedence over field names)You'll recall that the Screen system object allows you to refer to the form or control that.
We can use this with the Active. Form and. Active. Control properties to refer to the currently active form and its.
We use the dot operator because we are referring to properties: Screen. Active. Form! It can be easy to lose. Also, when you are stepping through your. Screen system object will not work. This can make code that uses. Screen system object difficult to test.
Referring to Controls on Subforms. If your form has a subform placed on it, you can refer to the subform and its controls. System. Object. Form. Name syntax. To Access, a. To refer to it, use the name of the control. Forms(. Using the Form property gets you into the subform.
Forms(. As with controls, you will generally want to read the. Unfortunately. many properties in Access are read- only during runtime.
This means that. you cannot change the value of a property while viewing the form. You. must open the form in design mode to change most properties. While this. can be fairly restrictive, a few important properties can be changed at. Of these, the Visible and Locked properties are particularly useful. Since properties are created by Access, you refer to them using the dot operator instead of the bang operator. Forms(. Using macros, you can control the data entry process, find.
Many of the macro commands you use will need to. For example. let's say you want to display a dialog box if the value in the. Order. Amount control is greater than 5. Attach the following macro. Order. Amount control's Before.
Update property: You can also refer to properties of forms and controls from your macro. For example, you could. Zip Code control disappear if an order was for a foreign. Use the Is. Null function to see if the value in the ctl. Country. control is blank, and if it is the Set. Value action sets the Visible.
Zip Code control to No. This will cause the control. Attach the following macro to the ctl. Country control's Before.
Update property: Notice that you didn't have to specify the full Forms(. In a macro, you can refer to a control name. Forms system object, or the form name.
Access knows. that you are referring to the form from which the macro was run. This is. an important shortcut: when a macro is called from a form, references to. Queries. You can refer to forms and controls in your queries.
This is useful if you want to use. Let's say. you have a button on your form named . When you press. this button, you want Access to run a query that finds all records from.
Orders table where the State is equal to the value of the State. First, create a query on the Orders table.
State control on the form. In Query design, enter. State field: Forms(. The user. could enter search criteria into an easy- to- use form, and your macro or.
Access VBA Modules. Modules are the place where object references really become powerful.
You have more. flexibility than in any other part of the Access. When you find that you.
VBA modules will open up a. In Access modules, you can refer to forms and controls using direct references as discussed. To refer to an object directly. The following. function displays a dialog box if the ctl. Order. Amount control contains an. This function puts the value 1.
Order. Amount control of the currently active form. Function Set. Amount(). Screen. Active. Form. Order. Amount = 1. Object Variables. While direct reference works, it is best to use object variables to refer to forms.
By using object variables, you assign a reference to a. This can reduce typing errors. You can also. assign shorter names to your objects, making your code easier to write. Finally, using object variables makes you program run. If the first two reasons didn't convince you, this one should. An object variable is different from a normal (numeric, string, etc.) variable in that it.
This is. an important concept: if you create multiple object variables and assign. VBA provides two object variable types that are useful when referring to forms and. The Form variable type is used to refer to a form. The Control. variable type is used to refer to a control on a form. There are two. steps necessary to use object variables.
You first declare the object. DIM statement. This creates the object variable. You then point the. SET statement. You must use both.
The following example is equivalent to the earlier function that displays a dialog box except, it uses Object Variables. Function Test. Amount(). Dim frm. Cust as Form.
Dim ctl. Amount as Control. Set frm. Cust = Forms(. These variables will hold references to. The next two lines assign real objects to the. Note that when we SET the control variable, we point.
Cust object variable, instead of directly referencing the. Forms system object. For the rest of the function, whenever you want to. Amount control, use the ctl. Amont variable. You can refer to subforms in much the same manner. The following function sets the value.
State. Tax control on the subfrm. Orders subform of the frm. Customer form to 1. Remember that not all properties can be changed. The following function opens the Orders form, and makes the State. Tax and Federal. Tax fields invisible. Function Set. Order.
Form(). Dim frm. Orders as Form. Dim ctl. State. Tax. Dim ctl. Fed. Tax as Control. Do. Cmd. Open. Form . For example, let's say you. Without. object variables, you would have to hard- code the name each control in.
What if you don't know the name of all controls? This. problem can be easily solved using a integer variable in place of a. When you use a variable in an object reference, surround. The following function uses this. Immediate Window.
The form variable is. Customers Form. The function then loops through each. Count property which contains the number of controls. For each control, the Debug.
Print method is used to display. Control's name in the Immediate window. Control. Name is a property of. Instead of explicitly. This has. the effect of referencing control number . Create a form and place an object frame control. Use the Cut and Paste functions from the.
Edit Menu to duplicate that control in different positions on the form. Save the form. under the name . The form is opened and assigned. A loop is created to step through each control (assuming there are 2.
Visible. property of the current control to true, and setting the Visible property of the previous control to False. The Repaint. Object command is. Run the function from the immediate window, or from a macro. You will see a. control that appears to move from one location on the form to another.
Summary. You should now feel comfortable referring to forms and controls. If you understand the concepts of System Objects, Identifier Operators, and Object Variables. As you try these examples, you will. Don't be afraid to experiment. Good luck! Copyright . All rights reserved. This information may not be republished, reprinted or retransmitted in any.
FMS, Inc. The information provided in this document is provided.
VBA Tutorials - Lesson 0. Introduction to Microsoft Access and VBAThe Size of a Form or Report. The Width of a Form or Report. The width of a form or that of a report is the distance from its left border to its right border. To widen or narrow a form or report, click and drag the right border: The Height of a Form or Report. The height of a form or report is controlled by its sections. The Width and Height of a Form or Report.
To change both the width and the height of a form or report at the same time, position the mouse on. Then click and drag left, right, up, down, or diagonally.
Automatically Sizing the Form to Fit Its Content. If you want to resize a form enough to show its whole content, on the Ribbon, click Home.
In the. Window section, click Size To Fit Form. Controls Fundamentals. Introduction A Windows control, or simply called a control, is an object.
Microsoft Access supports various types of controls. Adding a Control to a Form or Report.
To manually add a control to a form or report, the form or. Design View. When that. Ribbon displays various objects in its Controls section. To add a control to a form or report, click it. Controls section of the Ribbon, and click the desired section of the form or report.
You can then move and. Practical. Learning: Adding a Control to a Form. In the Controls section of the Ribbon, click the Text Box. Click the wide area on the formu. Microsoft Visual Basic Fundamentals. Introduction. You can create a completely functional database using only Microsoft Access.
In some cases, to get. To support this, Microsoft Access ships with, and installs, a. Microsoft Visual Basic. This is a (smaller) variant of the popular Microsoft Visual Basic. Practical. Learning: Starting Microsoft Access. Start Microsoft Access.
In the list of files, click Exercise. Opening Microsoft Visual Basic. In order to access Microsoft Visual Basic, you must first create or open a database in Microsoft. Access. Then, you can open Microsoft Visual Basic from Microsot Access. You have various options. To launch Microsoft.
Visual Basic: Any of these actions would open Microsoft Visual Basic: Practical. Learning: Opening Microsoft Visual Basic. On the Ribbon, click Database Tools. Click the Visual Basic button. Primary Accessories for Programming and Code Writing. Introduction. When using a database, you are in fact using two applications to.
Microsoft Access is used to design the necessary objects. This means that Microsoft Access is used for its visual. On the other hand, Microsoft Visual Basic is used to handle. The Compiler. The code you will write is made of small instructions written in plain English, in a version.
Visual Basic language. The instructions you write must be translated in a language the computer. This is done by a program called a compiler. That program works behind the scenes so you will.
Comments. A comment is a piece of text in a code section that the. As such, a comment can be written any way you want.
In Visual Basic, the line that contains a comment can start. Here is an example: Private Sub Form. Here is an. example: Private Sub Form. They can never hurt your code and they don't increase. Comments can help you and other people who read.
Fundamentals of Modules. Introduction. A module is a file that holds programming code or pieces of code in a Visual Basic.
There are three types of modules you will use. A Module from a Form or Report. From Microsoft Access, if you use a form or a report to open its code, Microsoft Visual Basic.
Practical. Learning: Creating a Form- Based Module. To return to Microsoft Access, on the main menu of Microsoft Visual Basic. File and click Close and Return to Microsoft Access. On the Ribbon, click Create. In the Forms section, click Form Design.
Right- click the tab of the form (Form. Save. Set the name as Central. Click OKTo start a form module, with the form opened in Design View, on the Ribbon. Tools section of the Design tab, click the View. Code button. To return to Microsoft Access, on the Standard toolbar, click the View Microsoft Access button. A Module from Scratch. As another category, you can create a module that is independent of any form or report.
You can. then write any code you want in that file. To create a module: The names of modules are cumulative. This means that the first module would be named Module. Module. 2, etc. It is a good idea to have names that are explicit especially if your application. To give a custom name to a module, you must save it.
This would prompt you to name. You can accept the suggested name or type your own and press Enter.
Practical. Learning: Creating an Independent Module. In Microsoft Access and on the Ribbon, click Create. To start a module, on the Macro & Code section, click the Module button. Introduction to the Events of a Control.
An event is an action that occurs on a control. Examples of actions include clicking a button. Except for the label (or for static controls), every control supports some events. For example, a button is more likely to be clicked; so the default event. There are various ways you can launch an event for a. As one option, in Microsoft Access, right- click the control on a form. Build Event.. In the Event Builder dialog box, click Code.
Builder and click OK. If you are already working in Microsoft Visual Basic, in.
Object combo box, select the control. In the Procedure combo box, select the. Practical. Learning: Introducing Controls Events Right- click an unoccupied area of the form and click Build Event.. In the Choose Builder dialog box, click Code Builder. Click OKIn the Object combo box of Microsoft Visual Basic, select Form. Close Microsoft Visual Basic.
Close Microsoft Access. When asked whether you want to save, click No.
Microsoft Visual Basic Child Windows. Introduction. The Microsoft Visual Basic application is equipped with various windows you can use to create and. The windows are dockable. This means that they can be moved on the screen to other locations. The Project Window. The Project window displays the coding segments for the objects of your project. If the Project Explorer is not displaying and you need it.
View - > Project Explorer. The Project window is usually positioned on the left of the window. To move it, click its.
Standard toolbar, hold your mouse down and. To position it back to its previous location, double- click its title bar.
To expand or collapse the folders. Toggle Folders button. Introduction to the Properties Window.
In the Microsoft Visual Basic Environment, the Properties. The Code Editor. The Code Editor is the area where you will write code. It is. the largest section of the Microsoft Visual Basic programming environment. It is mainly made of three sections: On top, there are two combo boxes. To know the name of a combo box, you can position the mouse on. The Object combo box allows you to select a particular object and access its actions.
The Procedure. combo box allows you to select an action, related to the object in the Object combo box. The Code Editor is equipped with a vertical and a horizontal scroll bars. There are two small buttons on the left side of the horizontal scroll bar. The Full Module View. The Procedure View button will display the procedures associated. The Options Dialog Box. The Code Editor uses default colors to show the code.
To customize these. Editor Format property page of the Options dialog box. To access it, on the main menu, click. Tools and click Options..: The Immediate Window. The Immediate window is used to test code when. To display it, on the main menu of Microsoft Visual Basic, lick View - > Immediate Window.
Practical. Learning: Using Microsoft Visual Basic Windows. To display the immediate window, on the main menu of Microsoft Visual. Basic, click View and click Immediate Window. To use it, in the Immediate window, type ?
Enter. To return to Microsoft Access, on the Standard toolbar, click View. Microsoft Access. Microsoft Access Databases.
Introduction. There are various types of databases you can use in. Microsoft Access.
You can create a database from scratch. You can use some. Microsoft Access to create a database. You can open. either a database you previously created or one made by someone else.
Visually Creating a Microsoft Access Database. There are various ways you can create a database. To. visually start a database from scratch, after launching Microsoft Access, click Blank. Desktop Database. In the right section, accept or change the name of the database. If. you want to create a contemporary database, either omit or add the . If you want to create a database that is compatible with.
Microsoft Access, you must add the extension . After specifying the name, to specify a folder of your choice, under File Name and on. Browse button . You can click the arrow of the. Save In combo box to select a drive such as (A: ), (C: ), etc. After selecting the. Create New Folder button on the right side of the Save In combo.
You can also use a directory on the network as the. Creating a Database Using a Template. Microsoft Access ships with a few sample databases you can. To create a database from a template, after launching. Microsoft Access, in the middle section, locate and click the desired sample.
Deleting a Database. If you have a database you don't need anymore, you can.
To delete a database, in My Documents, in Windows Explorer or. C can click the database to select it and press Delete.
Right- click the database and click Delete. A warning message would be presented to you to confirm. Closing a Database. You can close a database without closing Microsoft Access. When you are in the Code Editor of Microsoft Visual Basic, you can get back to. Microsoft Access either from the View Microsoft Access button on the Standard toolbar or by clicking the Microsoft.
Access button on the Taskbar. The shortcut to get back to Microsoft Access is Alt + F1. You can close Microsoft Visual Basic any time and keep Microsoft Access running. To do this, on. the Standard toolbar of Microsoft Visual Basic, click the View Microsoft Access button to get back to the database.