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We all have limits, and an Access database is no exception. For example, an Access database has a size limit of 2 GB and can't support more than concurrent users. This guide gives you a smooth start to your SQL Server journey, helps preserve Access front-end solutions you created, and hopefully motivates you to use Access for future database solutions.
To successfully migrate, follow these stages. All Access database objects can either be in one database file, or they can be stored in two database files: a front-end database and a back-end database. This is called splitting the database and is designed to facilitate sharing in a network environment. The back-end database file must only contain tables and relationships.
The front-end file must only contain all other objects, including forms, reports, queries, macros, VBA modules, and linked tables to the back-end database.
When you migrate an Access database, it's similar to a split database in that SQL Server is acting as a new back-end for the data that is now located on a server. As a result, you can still maintain the front-end Access database with linked tables to the SQL Server tables. Effectively, you can derive the benefits of rapid application development that an Access database provides, along with the scalability of SQL Server.
Still need some convincing to migrate to SQL Server? Here are some additional benefits to think about:. More concurrent users SQL Server can handle many more concurrent users than Access and minimizes memory requirements when more users are added. Increased availability With SQL Server, you can dynamically backup, either incremental or complete, the database while it's in use.
Consequently, you do not have to force users to exit the database to back up data. High performance and scalability The SQL Server database usually performs better than an Access database, especially with a large, terabyte-sized database.
Also, SQL Server processes queries much faster and efficiently by processing queries in parallel, using multiple native threads within a single process to handle user requests.
Improved security Using a trusted connection, SQL Server integrates with Windows system security to provide a single integrated access to the network and the database, employing the best of both security systems. This makes it much easier to administer complex security schemes.
SQL Server is the ideal storage for sensitive information such as Social Security numbers, credit card data, and addresses that are confidential. Immediate recoverability If the operating system crashes or the power goes out, SQL Server can automatically recover the database to a consistent state in a matter of minutes and with no database administrator intervention.
Azure SQL Server In addition to the benefits of SQL Server, offers dynamic scalability with no downtime, intelligent optimization, global scalability and availability, elimination of hardware costs, and reduced administration. If you are migrating to Azure SQL Server, there are three options to choose from, each with different benefits:. A single database is like a contained database in SQL Server. You can also add an elastic pool, which is a collection of databases with a shared set of resources managed via the SQL Database server.
The most commonly used SQL Server features are available with built-in backups, patching, and recovery. But there is no guaranteed exact maintenance time and migration from SQL Server might be hard. Managed instance This option is a collection of system and user databases with a shared set of resources.
A managed instance has built-in backups, patching, recovery, and is easy to migrate from SQL Server. However, there are a small number of SQL Server features that are not available and no guaranteed exact maintenance time. You have full control over the SQL Server engine and an easy migration path. But you need to manage your backups, patches, and recovery. There are a few issues you can address up front that can help streamline the migration process before you run SSMA:.
Add table indexes and primary keys Make sure each Access table has an index and a primary key. SQL Server requires all tables to have at least one index and requires a linked table to have a primary key if the table can be updated.
SQL Server does not support joined columns with different data types and sizes in foreign key constraints. If the database is in. Back up your database.
For more information, see Protect your data with backup and restore processes. Tip Consider installing Microsoft SQL Server Express edition on your desktop which supports up to 10 GB and is a free and easier way to run through and check your migration. When you connect, use LocalDB as the database instance. Tip If possible, use a stand-alone version of Access.
SSMA mainly migrates tables and select queries with no parameters. Forms, reports, macros, and VBA modules are not converted. These two connections are saved in your migration file should you decide to transfer additional objects in the future. Note The migration process can take some time depending on the size of your database objects and the amount of data that must be transferred. Make sure you install the appropriate 32 or 64 bit version for your computer.
After installing SSMA, open it on your desktop, preferably from the computer with the Access database file. You can also open it on a machine that has access to the Access database from the network in a shared folder. Follow the beginning instructions in SSMA to provide basic information such as the SQL Server location, the Access database and objects to migrate, connection information, and whether you want to create linked tables.
The rowversion field helps avoid record conflicts. Access uses this rowversion field in an SQL Server linked table to determine when the record was last updated. Also, if you add the rowversion field to a query, Access uses it to re-select the row after an update operation.
This improves efficiency by helping to avoid write conflict errors and record deletion scenarios that can happen when Access detects different results from the original submission, such as might occur with floating point number data types and triggers that modify columns. However, avoid using the rowversion field in forms, reports, or VBA code.
For more information, see rowversion. Note Avoid confusing rowversion with timestamps. Although the keyword timestamp is a synonym for rowversion in SQL Server, you can't use rowversion as a way to timestamp a data entry. For example, if you only store English text, you can use the varchar rather than nvarchar data type.
As a best practice, use the SSMA assessment report, which shows the conversion results, including errors, warnings, informational messages, time estimates for performing the migration, and individual error correction steps to take before you actually move the objects.
Converting database objects takes the object definitions from the Access metadata, converts them into equivalent Transact-SQL T-SQL syntax , and then loads this information into the project.
Tip Once you have successfully migrated your Access database, save the project file for later use, so you can migrate your data again for testing or final migration. You can install the drivers on each computer where the converted database is used. After you migrate the Access tables, you can link to the tables in SQL Server which now hosts your data. Linking directly from Access also provides you with a simpler way to view your data rather than using the more complex SQL Server management tools.
You can query and edit linked data depending on the permissions set up by your SQL Server database administrator. Tip Don't forget to use the Linked Table Manager in Access to conveniently refresh and relink tables. For more information, see Manage linked tables. The following sections describe common issues you can encounter during migration and how to deal with them. Only Select Queries are converted; other queries are not, including Select Queries that take parameters.
Some queries may not completely convert, and SSMA reports query errors during the conversion process. You can manually edit objects that do not convert by using T-SQL syntax. Syntax errors may also require manually converting Access-specific functions and data types to SQL Server ones. You can use this data type to efficiently calculate large numbers but it requires using the Access 16 For more information, see Using the Large Number data type and Choose between the bit or bit version of Office.
Date and Time There are several date and time considerations:. If the compatibility level of the database is SQL Server or higher, and a linked table contains one or more datetime or datetime2 columns, the table may return the message deleted in the results.
When querying for dates in SQL Server, take into account the time as well as the date. For example:. Attachment The Attachment data type stores a file in Access database. In SQL Server, you have several options to consider. You can extract the files from the Access database and then consider storing links to the files in your SQL Server database.
By default, these columns will be converted to nvarchar max columns in SQL Server, but you can customize the mapping to choose a smaller data type. In your Access solution, you can still use the hyperlink behavior in forms and reports if you set the Hyperlink property for the control to true. Multivalued field The Access multivalued field is converted to SQL Server as an ntext field that contains the delimited set of values.
Because SQL Server does not support a multivalued data type that models a many-to-many relationship, additional design and conversion work might be needed. Note Multivalued fields are not converted and were discontinued in Access For more information, see Date and time types , String and binary types , and Numeric types. In most cases, these queries should be converted to pass-through queries. SQL Server cannot run these user defined functions.
You may need to manually redesign these functions and convert them to stored procedures on SQL Server. By far, the most important way to optimize performance with your new, back-end SQL Server is to decide when to use local or remote queries. When you migrate your data to SQL Server, you are also moving from a file server to a client-server database model of computing.
Follow these general guidelines:. For more information, see Create a pass-through query. Put logic on the server Your application can also use views, user-defined functions, stored procedures, calculated fields, and triggers to centralize and share application logic, business rules and policies, complex queries, data validation, and referential integrity code on the server, rather than on the client.
Ask yourself, can this query or task be performed on the server better and faster? Finally, test each query to ensure optimal performance.
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