What is the difference between an instance name and a database name in a database? __ Database

If you have used the database, then the connection to the database configuration will not be unfamiliar, whether you are using a mature framework and your own use of JDBC implementation, can not escape that several important information, but there is an important configuration, I used to have been so-so, superficial understanding, But this kind of thing encounters many to feel very afflictive, therefore decided to solve this problem today.

The following article is for SQL Server databases only:

The content of this article comes from the following links: http://www.experts-exchange.com/questions/28411445/ Whats-the-difference-between-a-database-name-and-instance-name-in-sql.html

a database contains multiple table structures that store real data, while an instance contains multiple databases, and a single server (hardware) can contain multiple instances .

Each instance is a SQL Server-installed component (or the database engine's programs, tools, and related programs). Each user database (and table) is created by writing code, using tools, and copying/restoring an existing database. When you install a SQL Server program, you can install a different instance on a single machine by naming it. For example, you can have sql2005,sql2008,sql2012 as a separate named instance of SQL Server. You can also install the same version into different instances, such as SQL2005DW (for data warehouses), Sql2005_pay (payroll), SQL2005_ERP, and so on.

You can have one (and only) instance that is called the default instance, and all other instances must have a name (16 characters) on the same machine.

This program (SQL Server database engine) competes with each other for machine resources, so you must understand and manage how each instance will compete, otherwise they will slow down or even stop the machine.
Perhaps more often than not, there are multiple databases in one instance. Each instance has a system database (MASTER,MODEL,RESOURCES,MSDB,TEMPDB), and you can then create your own user database in that instance.
In managing server resources, you can manage how much memory and CPU each instance requires. However, you cannot do this for a database in an instance.
You can apply security and access restrictions at two levels of an instance or database. Although sometimes the business may be more inclined to use highly sensitive/security-related data as a separate instance (e.g. Payroll database) to avoid any danger.
When connecting to a database, both the instance name and the database name must be provided.

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The default instance of SQL Server and the file location of the named instance
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The difference between ORACLE global database name/database instance/oracle_sid