Database objects include: users (people with permission to access the database), views (displaying data items needed by users), indexes (providing users with a way to quickly access data), triggers (user-defined SQL A collection of transaction commands), a sequence (a sequential table that provides unique values), and a diagram (a diagram of a relationship between database tables).
The main database objects are
User
In fact, users refer to people who have permission to access the database.
View(View)
The view also has a set of data items and named fields, which only appear when the user performs a query operation. In fact, they do not exist in the database. Exist, by controlling users' access to data, simplifying data and displaying only the data items users need.
Index
The index is to provide users with a quick way to access data, monitor the data of the database table at all times, and build it with reference to specific database table columns. A sequence, mainly to facilitate users to access specified data and avoid duplication of data.
Trigger (Trigger)
Trigger belongs to the user-defined set of SQL transaction commands in the database table. If you delete, insert, or modify a database table, the command can be executed automatically.
Sequence
Sequence, the definition is stored in the data dictionary. The sequence provides a sequence table of unique values to simplify the design of the program.
Diagram
Diagram is for editing the relationship between tables. It can be understood as a schematic diagram of the relationship between database tables.
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