A macro is a set of one or more actions (action: The basic building block of a macro; a self-contained instruction that can be combined with other actions to automate tasks. This is sometimes called a command in other macro languages.) that each perform a particular operation, such as opening a form or printing a report. Macros can help you to automate common tasks. For example, you can run a macro that prints a report when a user clicks a command button.

When you create a macro, you enter the actions you want to carry out in this portion of the Macro window (Macro window: The window in which you create and modify macros.).

You can specify arguments for an action in this portion of the window.

A macro can be one macro composed of a sequence of actions, or it can be a macro group (macro group: A collection of related macros that are stored together under a single macro name. The collection is often referred to simply as a macro.). You can also use a conditional expression (conditional expression: An expression evaluated and compared to a value; for example, If...Then and Select Case statements. If the condition is met, one or more operations are performed. If it isn't met, the operation is skipped.) to determine whether in some cases an action will be carried out when a macro runs.

The following macro is composed of a series of actions. Microsoft Access carries out these actions each time the macro runs. To run this macro, you refer to the macro name Review Products.

If you have numerous macros, grouping related macros in macro groups (macro group: A collection of related macros that are stored together under a single macro name. The collection is often referred to simply as a macro.) can help you to manage your database more easily.

For example, the following macro group, named Buttons, is made up of three related macros: Employees, Products, and Reps. Each macro carries out the OpenForm action, and the Products macro also carries out the MoveSize action.

The name in the Macro Name column identifies each macro. When you run a macro in a macro group, Microsoft Access carries out the action in the action column and any actions that immediately follow with a blank Macro Name column.

You can run a macro in a macro group in an event or event procedure (event procedure: A procedure that is automatically executed in response to an event initiated by the user or program code, or that is triggered by the system.) by typing the macro group name followed by a period and then the macro name. In the preceding example, to refer to the Employees macro in the Buttons macro group, you would type Buttons.Employees.

In some cases, you may want to carry out an action or series of actions in a macro only if a particular condition (condition: Part of the criteria that a field must meet for searching or filtering. Some conditions must be used with a value; for example, the field Author with the condition equals with the value Jane.) is true. For example, if you're using a macro to validate data in a form, you might want to display one message in response to one set of values entered in a record and another message in response to a different set of values. In cases like these, you can use conditions to control the flow of the macro.

A condition is a logical expression (expression: Any combination of mathematical or logical operators, constants, functions, and names of fields, controls, and properties that evaluates to a single value. Expressions can perform calculations, manipulate characters, or test data.) that evaluates to True/False or Yes/No. The macro follows different paths depending on whether the condition is true or false.

When you run the macro, Microsoft Access evaluates the first conditional expression (conditional expression: An expression evaluated and compared to a value; for example, If...Then and Select Case statements. If the condition is met, one or more operations are performed. If it isn't met, the operation is skipped.). If the condition is true, Microsoft Access carries out the action in that row and any of the immediately following actions that are preceded by an ellipsis (...) in the Condition column.

Microsoft Access then runs any additional actions in the macro that have a blank Condition column until it reaches another expression, a macro name, or the end of the macro.

If the condition is false, Microsoft Access ignores the action and any immediately following actions that are preceded by an ellipsis in the Condition column and moves to the next action row (action row: A row in the upper part of the Macro window in which you enter macro names, actions, conditions, and comments associated with a particular macro or macro group.) that contains another condition or a blank Condition column.

The following macro runs the MsgBox and the StopMacro actions only when the expression in the Condition column is true (when there is a Null (Null: A value you can enter in a field or use in expressions or queries to indicate missing or unknown data. In Visual Basic, the Null keyword indicates a Null value. Some fields, such as primary key fields, can't contain Null.) value in the SupplierID field).

Action arguments are additional information required by some macro actions— for example, the object affected by the action or special conditions under which the action is carried out. After you add an action to a macro, you set the arguments for the action in the lower portion of the Macro window (Macro window: The window in which you create and modify macros.). These arguments give Microsoft Access additional information on how to carry out the action.

Tips for setting action arguments:

• In general, it's a good idea to set action arguments in the order they're listed, because choices for one argument may determine those for arguments that follow.
• If you add an action to your macro by dragging a database object (database objects: An Access database contains objects such as tables, queries, forms, reports, pages, macros, and modules. An Access project contains objects such as forms, reports, pages, macros, and modules.) from the Database window (Database window: The window that appears when you open an Access database or an Access project. It displays shortcuts for creating new database objects and opening existing objects.), Microsoft Access automatically sets appropriate arguments for that action.
• If an action has an argument that calls for the name of a database object, you can set the argument and the corresponding object type argument automatically by dragging the object from the Database window to the argument box.
• You can use an expression (expression: Any combination of mathematical or logical operators, constants, functions, and names of fields, controls, and properties that evaluates to a single value. Expressions can perform calculations, manipulate characters, or test data.) preceded by an equal sign (=) to set many action arguments.