- A schema is a blueprint for a database that ensures optimal organization
- Determining the database schema
- Why schedules are important
- Create charts
- Schemas vs Data Models
A schema is a blueprint for a database that ensures optimal organization
database schema is a set of metadata that describes relationships between objects and information in a database. An easy way to represent a schema is to think of it as a block of tables, stored procedures, views, and associated data assets. The scheme defines the infrastructure of this block.
Determining the database schema
At the most basic level, a schema serves as a container for data assets. However, different database vendors use schemas differently. For example, Oracle treats each schema as a user account. To create a new schema, the DBA creates a new database user with the intended schema name.
The schema does not match the data model.
Why schedules are important
Because schemas are a structural element of a database, most database environments enforce permissions on schema-level objects.
For example, a company database may contain a number of users. Each user uses a scheme, but access to different schemes is granted separately and with granular permissions to users outside the home scheme.
Most database management tools do not list schemas; instead they list databases and users.
For example, a company creates user accounts (schemas) for Bob and Jane. He also creates accounts for departments such as HR and marketing. An analyst in each department is then granted access to the department schedule account.
The HR analyst creates tables and views in the HR schema and gives Bob read (but not write) access to a table of employee names and employee ID numbers. Alternatively, the Human Resources analyst can grant Jane read/write access to a table of employee phone numbers.
By granting access in this way, only the appropriate roles and users can read, write, or modify the data in the offline data source in the larger database.
Every database engine considers schemas to be the fundamental method of separating data in a multi-user environment.
Different database engines treat users and schemas differently. Refer to the documentation specific to your database engine for specific syntax and logical models around users, schemas, and permissions.
The schema is formally defined using Structured Query Language. For example, in Oracle, you create a schema by creating a user account that it owns:
CREATE USER bob
ИДЕНТИФИЦИРОВАНО временным паролем
Пример DEFAULT TABLESPACE
Пример QUOTA 10M ON
ВРЕМЕННЫЙ ПАРАМЕТР TABLESPACE temp
QUOTA 5M ON система
PROFILE app_user ПАРОЛЬ EXPIRE;
Other users can access the new schemes based on their username or one or more roles to which the user account has been added.
Schemas vs Data Models
The schema has no internal structure to do anything; instead, it is a framework to support consent segmentation in the database. However, the conditions scheme and data model are used interchangeably.
Usage scheme to discard confusingly, but not incorrectly, references to a specific set of tables and views related by certain relationships. The schema-as-architecture approach described in this article is a version of diagrams with a capital S. The relationship between schema and data is a small version of S – a synonym. Many help sites on the Internet make this essential distinction unnecessary.
A data model is a set of tables and views that are joined together by certain keys. Together, these data assets serve a business purpose. It is perfectly acceptable to apply a data model to a schema. In fact, for large and complex data models, mapping them to schemas enables intelligent database management. But logically there is no need to use a schema for a data model, or to treat a data model as a schema.
For example, an HR department may include a data model in its schema to analyze employee performance. Instead of creating a schema for these checks, the data model can reside in the HR schema (along with other data models) and remain logically distinct through table prefixes and display names for objects in the data model.
The data model can be given an informal name, such as: performance appraisals and then all tables and views can be prefixed pr_ † The employee list table may be referred to as: hr.pr_employee without the need for a new schedule for performance reviews.