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New Perspectives on Microsoft Office Access 2003 Tutorial 12
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Microsoft Office Access 2003
Tutorial 12 – Managing and Securing a Database
New Perspectives on Microsoft Office Access 2003 Tutorial 12
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XPAnalyze a database's performance
• Analysis tools will help you provide a database that runs as efficiently as possible.
• The Performance Analyzer will produce a list of ideas, suggestions, and recommendations.
• However, many of the suggestions and recommendations can be carried out for you.
• If you decide to allow Access to fix the problem, you will be able to check the results by viewing the objects pertaining to the suggestion.
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XPThe Performance Analyzer dialog box
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XPThe Performance Analyzer analysis window
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XPView and print database documentation
• If you want to print a graphical view of the relationships in your database, you can have Access print the relationships window.
• This will print exactly what you see when you open this window. • If you need to have more detailed information about the objects in the
database, you can run the Documenter.• In the Documenter, you can choose what objects to include in the
Documenter's report and you can make several choices as to what should be included in the report.
• When you are finished making your selections, you will received a very detailed report containing Field names, Field types, Field sizes, relationships with other objects, etc.
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XPLink a database to a table in another database
• There will be times when you will want to make an Access table available to a user for data entry, but you would not want them to be able to change the structure of your table.
• You can do this by providing a linked table in the database.
• A linked table is a table that is stored in a file outside the open database.
• Access will be able to update and retrieve records in the open database but will disallow changes to the structure of the table.
• When you establish a link to a table in the database, the linked table shows up on your list of table objects but the icon looks different.
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XPThe Link Tables dialog box
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XPUse the Linked Table Manager
• When you link to a table, Access keeps track of where that table is stored.
• If you move the location of the database to a different folder, Access won't know where it is.
• You can use the Linked Table Manager to refresh the link to the table so that Access will be able to find the linked table.
• In the Linked Table Manger, point to the new location, and Access will then update the link information.
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XPThe Linked Table Manager dialog box
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XPUse replication to create a Design Master and replica of a database
• Sometimes there will be multiple users updating database data.
• If you gave each one a copy of the database and allowed them each to make changes in their copy, it would be quite difficult to pull all the changes together later into a single database.
• However, replication makes it easy to handle this kind of activity.
• When you create a replica of a database, you create a special copy of the database and the original copy becomes the Design Master of the database.
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XPUpdate Design Masters from replica sets
• The Design Master and all of the replicas that have been made of it are called the replica set.
• Once you have created a replica set, Access keeps track of the changes that eventually will be incorporated into the Design Master.
• Any changes in the data in any replicas can be updated automatically in the Design Master through a process called synchronization.
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XPThe Database Window for a Design Master
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XPSynchronize the Design Master and replica Data
• When you have a replica set, you can synchronize the records in the replica database(s) by running the Synchronize Database process. – When the synchronization process is run, Access will check for changes
in the data in the replica database(s) and, if any, will incorporate those changes into the Design Master.
• After the synchronization process is complete, you will be able to see the changes that have been made in the replica database(s) in the Design Master database.
• When you no longer need the replica(s), you should delete them.
• If there are no replicas being used, you should rename the Design Master to its original name.
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XPThe Synchronize Database dialog box
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XPSplit a database
• A database developer often will separate the interface to a database (its queries, forms, and other database objects) from the actual database data. This is known as splitting the database.
• The Database Splitter splits the database into two databases.
• The database that contains the actual data is called the back-end database.
• The database that contains the other objects is called the front-end database.
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XPThe Database Splitter dialog box
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XPFront-end versus back-end database
• The users of the database will work through the front-end database to add, modify, and delete data in the back-end database.
• The developer does not make changes to the back-end database but periodically makes changes to the front-end database by updating its queries, forms, and reports.
• In a network environment, the back-end database is usually stored on the network where users can access it.
• The Front-End database is stored on all the user computers, as it is their interface to the back-end database.
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XPAn illustration of splitting a database
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XPSet database startup options
• There are several options that can be set to be initiated at the time the database is opened.
• These options are called Startup Options and can be set by clicking Tools on the menu bar and then click Startup.
• On this Startup dialog box, you can specify a particular form you want to display when the database is opened.
• You can also choose from several options related to how much access users will have to the menu and toolbars.
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XPThe Startup dialog box
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XPImplement database security
• Databases often have sensitive data that must be protected.
• Security refers to the protection of a database against unauthorized access.
• Startup options offer a degree of security but there is more that you could do to protect the data.
• You can use Encryption, Decryption, and Passwords to protect your database.
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XPEncrypt and decrypt a database
• Encryption is a process that will convert the data in a database to a format that is unreadable. – If a user is able to gain access to a database that is encrypted, the
data could only be read if it was decrypted
• Decrypting a database is the process of returning the encrypted data to its original state.
• Another form of security includes the use of passwords. – Passwords applied to a database makes it impossible to open the
database unless you know the password
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XPSet and unset a database password
• If data is very important and meant to be viewed only by authorized users, it is a good idea to assign a password to the database.
• When you set a password, you usually establish exclusive access, meaning that only one user can access the database at a time.
• You can also set the password so that the database is opened as Read-Only, meaning that no changes can be made to the database.
• In order to remove the password, you must use the password to get into the database and unset (or cancel) the password.
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XPThe Set Database Password dialog box
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XPImplement user-level security
• The security measures discussed in previous sections apply to all users of the database.
• Sometimes you will want to allow some users access rights and disallow those rights for other users.
• You can accomplish this by setting user-level security.
• User-level security lets you grant users or groups of users specific permission to tables, queries, forms, reports, and macros.
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XPAssign users permissions to a database
• You can assign each user a set of permissions, which specify what that particular user has rights to.
• You can specify that a user can modify data or can only read data.
• You can specify whether the user is allowed to delete data.
• This kind of activity is usually managed by a person designated as the database administrator, or a group of people called the database administration (DBA) group.
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XPAssign group permissions for multiple users
• The DBA will be responsible for controlling and assigning permissions to certain users.
• Because there are often groups of people who should have the same permissions, the DBA can assign permissions to groups rather than individuals.
• Usually there is a workgroup information file that maintains group names, user names, passwords, and group membership information.
• This information is stored in hidden files and is available only to the DBA.
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XPAn illustration of user-level security
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XPUse the Security Wizard to assign permissions
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XPProtect VBA code from unauthorized changes
• Database developers often work long, tedious hours writing VBA code to augment the functionality of the database.
• Usually, the developer will want to protect the code from unwarranted changes.
• The code is readily available in the modules of the database unless the code is converted.
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XPCreate an MDE file
• You can save a database as an MDE file, which compiles all the VBA code into machine code and removes the VBA source code.
• The database will still work exactly as it did prior to this conversion, but no one will be able to alter the code because they will not be able to get to it.
• In Access 2003, you must make sure the database is in 2002 format before you try to convert it to an MDE file.
• This process is not always necessary and should only be done if there are many VBA modules in the database and the code must be protected from changes.
