Use the Instance Name page of the SQL Server Installation Wizard to specify whether to create a default instance or a named instance of SQL Server. A default instance name is used unless you choose a named instance.
Each SQL Server instance is made up of a distinct set of services with specific settings for collations and other options. The directory structure, registry structure, and service names all reflect the specific instance ID of the SQL Server instance created during SQL Server Setup.
An instance is either the default instance or a named instance. The default instance name is MSSQLSERVER; it does not require a client to specify the name of the instance to make a connection. A named instance is determined by the user during Setup.
A named instance can be installed at any time. By default, the first time you install SQL Server 2005 on a computer, Setup specifies the installation as the default instance; however, you can choose to install SQL Server as a named instance without installing the default instance first. The default instance could be an installation of SQL Server version 6.5, 7.0, 2000, or 2005. Only one installation of SQL Server, regardless of version, can be the default instance at any one time.
Use the Instance Name page of the Microsoft SQL Server Installation Wizard to specify whether to create a default instance or a named instance of SQL Server Express. SQL Server Express always installs a named instance (SQLExpress) unless you select a default instance. This behavior differs from SQL Server 2005, which installs a default instance unless a named instance is selected.
Options
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Option |
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Default instance |
If you select Default instance and a default instance already exists on the machine, SQL Server Setup will upgrade the default instance. Choose this option to install a default instance of SQL Server Express. A computer can host only one default instance. |
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Note: |
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The default instance name is MSSQLSERVER; it does not require a client to specify the name of the instance to make a connection. |
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To upgrade the default instance of a previous SQL Server installation, click Default Instance and then click Next. |
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Named instance |
When you run SQL Server Express, by default, the named instance option is selected with SQLExpress as the instance name. Choose this option to create a new named instance. Consider the following when you name an instance of SQL Server: Instance names are not case sensitive. Instance names cannot contain the terms Default, MSSQLServer, or other reserved keywords. If a reserved keyword is used in an instance name, an error will occur. Instance names are limited to 16 characters. The first character in the instance name must be a letter or an underscore (_). Acceptable letters are those defined by the Unicode Standard 2.0, including Latin characters a-z and A-Z, and letter characters from other languages. Subsequent characters can be letters defined by the Unicode Standard 2.0, decimal numbers from Basic Latin or other national scripts, the dollar sign ($), or an underscore (_). Embedded spaces of other special characters are not allowed in instance names, nor are the backslash (), comma (,), colon (:), semi-colon (;), single quotation mark (‘), ampersand (&), number sign (#), or at sign (@). |
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Note: |
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Only characters that are valid in the current Microsoft Windows code page can be used in SQL Server instance names. If an unsupported Unicode character is used, an error will occur. |
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Installed Instances |
Use the Installed Instances page of the SQL Server Installation Wizard to view a list of installed SQL Server Express instances and components on the computer where SQL Server Setup is running. The Installed Instance Details pane displays upgrade options for installed instances. To select a component or instance to upgrade, click the instance name and then click OK. |
