Introduction to SQL Server Synonym
The SQL Server synonym, also known as an alias or alternative name, is a tool that many developers and database administrators use to simplify object names and abstract away physical storage locations. A synonym is a virtual object that allows you to refer to a database object using a different name.
Instead of using a lengthy object name or a fully qualified name that requires a detailed understanding of the database schema, you can create a synonym to provide a simpler and more abstract name.
Benefits of using Synonyms in SQL Server
There are several benefits of using synonyms in SQL Server. Firstly, synonyms help in abstraction, which means you can create a synonym for an object without worrying about its physical location or name.
This abstracts away the complexity of the database schema and allows you to use simple names to refer to complex objects. Secondly, creating a synonym can simplify the object reference names, which can help to improve code readability and maintenance in the long run.
Finally, synonyms come in handy when you need to change the name or location of an object without breaking the existing code.
Creating SQL Server Synonyms
To create a synonym in SQL Server, you use the CREATE SYNONYM statement. The syntax for creating a synonym includes the keyword CREATE SYNONYM, followed by the synonym name and the FOR clause, which specifies the object that the synonym points to.
For example, if you want to create a synonym for a table named sales.orders, you could use the following code:
CREATE SYNONYM orders FOR sales.orders;When you query the orders synonym, you will be referred to the sales.orders table. You can create a synonym within the same database or even create a synonym for a table in another database.
Example of creating a synonym within the same database
If you are working with a database named AdventureWorks2019 and you want to create a synonym for a table named sales.orders, you can use the following code:
USE AdventureWorks2019
GO
CREATE SYNONYM orders FOR sales.orders;Once you create the orders synonym, you can reference the sales.orders table by using the shorter synonym name.
Example of creating a synonym for a table in another database
If you want to create a synonym for a table in another database, you need to provide the fully qualified name of the object. Suppose you want to create a synonym for a table named suppliers in a test database, you can use the following code:
CREATE SYNONYM suppliers FOR test.dbo.suppliers;The synonym name ‘suppliers’ can now be used to reference the ‘suppliers’ table even if it resides in a different database.
Listing all synonyms of a database
If you want to list all existing synonyms of a database, you can use the sys.synonyms catalog view or view synonyms through SQL Server Management Studio. The catalog view ‘sys.synonyms’ contains one row for each synonym in the current database and shows details such as the name and object that the synonym points to.
Summary
The SQL Server synonym is a powerful tool that can help you simplify object names, abstract away physical storage locations, and make code more readable and maintainable. Unlike renaming the object itself, creating a synonym is a simple and efficient way to assign a virtual name to a database object.
Therefore, it is a useful feature to include in your development or administrative work with SQL Server.
3) Removing SQL Server Synonyms
While synonyms are useful in simplifying object names and abstracting away physical storage locations, you may want to remove them when they are no longer needed. Removing a synonym is as easy as creating one, and you can do it using the DROP SYNONYM statement.
The syntax for the DROP SYNONYM statement includes the synonym name, and you can also include the IF EXISTS option to prevent errors if the synonym does not exist.
Here’s an example of how to remove a synonym named ‘orders’ in SQL Server:
DROP SYNONYM IF EXISTS orders;4) When to Use Synonyms
There are several scenarios where using synonyms can simplify database management and development.
Using Synonyms with Remote Servers
Firstly, synonyms can simplify object names when working with a remote server.
A remote server is a feature that allows SQL Server to access and work with data from other servers. When you create a synonym for a remote object, you can reference the object using the synonym name instead of the long and complex name required to specify the remote server’s physical location.
This makes coding easier, as developers can use the same object name to reference the object regardless of the physical location.
Enabling Seamless Object Name Changes
Secondly, synonyms can enable seamless object name changes, which means you can rename a database object without breaking existing applications that reference that object.
For instance, if you renamed a table that was frequently used in existing applications, those applications would break unless you changed all references to the new table name. Instead of changing every reference, you can create a synonym with the original table name and point to the renamed table.
Applications that reference the synonym continue to work without any changes to the application code.
Shortening Lengthy Object Names
Finally, synonyms can help to shorten lengthy object names, which can make code more readable and improve code management.
By creating a short and easy-to-remember synonym name, it becomes easier to manage code and understand the objects that the code references. This is especially useful when working with multiple tables, views or stored procedures across a large database systems where the object names can become very lengthy.
In conclusion, SQL Server synonyms are a powerful feature that can help to simplify object names, abstract away physical storage locations, and avoid breaking existing applications when making object name changes. You can use synonyms to create abstract virtual names for database objects, shortening the length of object names for easy management, and simplifying object names when working with remote servers.
Removing a synonym is easy using the DROP SYNONYM statement, and doing so helps to declutter the database environment. By utilizing the benefits of SQL Server synonyms, you can improve code readability, ease of development, and simplify the management of database objects.
In conclusion, SQL Server synonyms are a valuable tool that can simplify object names, abstract away physical storage locations, and enable seamless object name changes. Synonyms can be easily created and removed using the CREATE SYNONYM and DROP SYNONYM statements.
By utilizing synonyms, you can shorten lengthy object names, simplify object names when working with remote servers, and make code more readable and maintainable. Overall, SQL Server synonyms should be a part of every developer’s and database administrator’s toolkit to simplify database management and development.