- SQL Server Instance = The running process of SQL Server, which manages databases.
- Database = A collection of data inside an instance.
- Schema = A logical namespace inside a database to organize objects.
- SQL Server (the program) runs instances.
- Each instance can manage multiple databases.
- Each database can have multiple schemas.
| Concept | Explanation |
|---|---|
| SQL Server (RDBMS) | The software you install that allows you to create, manage, and query relational databases. |
| SQL Server Instance | A running process of SQL Server that can manage one or more databases. |
| Database | A collection of tables, views, and objects managed by an instance. |
| Schema | A logical namespace inside a database to organize tables and other objects. |
SQL Server (RDBMS)
└── Instance: MSSQLSERVER
├── Database: ERP_DB
│ ├── Schema: hr
│ │ ├── Table: hr.employees
│ ├── Schema: finance
│ ├── Table: finance.invoices
├── Database: Retail_DB
├── Schema: store
├── Table: store.products
| RDBMS | Instance | Schemas |
|---|---|---|
| SQL Server | Yes (Named/Default) | Yes |
| PostgreSQL | Yes (Cluster-based) | Yes |
| MySQL | No (Single process) | No (Databases only) |