Learn the main content of Sybase SQL Server

Sybase SQL Server is a multi-database RDBMS with the following Architecture:

1. Database

The database used by the server itself can also be said to be the database used to manage the server and user database. Sybase automatically creates four system databases during installation:

Master, model, tempdb, sybsystemprocs

(1) master database

It is a core database for managing and controlling user databases and maintaining normal server operations. It stores a large amount of system information, such as server configurations, users, and devices.

Common users are not allowed to create database objects in the master database. Otherwise, the transaction logs of the master database will quickly become full. If the transaction logs are exhausted, you cannot use the dump transaction command to release the space in the master database.

(2) model database

It is a template provided to create a user database. Every time a new database is created, SQL Server automatically creates a copy of the model database and expands it to the size required by the user to serve as the new user database.

The model database contains the system tables required by each user database. The model database can be modified to customize the newly created database.

(3) tempdb Database

It is a temporary database that provides a shared storage area for server operation and processing. For example, the intermediate results of group by and order by are stored here. The space of tempdb is shared by all users of all databases on the server.

Every time you restart SQL server, an automatic process on the server copies the model database to the tempdb database and clears the original content in tempdb. Therefore, user tables in tempdb are temporary. Temporary tables are classified into two types: shareable and shareable. Temporary tables that cannot be shared are created by placing symbol # before the table name in create table. Temporary tables that can be shared are created by specifying the table name prefix tempdb .. In create table. SQL Server automatically adds a numeric extension to a temporary table that cannot be shared, and it only exists in the current session.

(4) sybsystemprocs database master database

It is a database dedicated to saving system commands (stored procedures), such as sp_help, sp_configure, sp_helpdevice, etc. When any database user runs a stored procedure starting with SP _, SQL Server searches for the current database, sybsystemprocs database, and master database in the following order.

2. User Database

User database is the real purpose of using the Sybase server. To manage user data, you must create your own database in Sybase. It refers to the database created using the create database Command. Users who cannot access the master database do not have the right to create a new database.

The main content in the database-database object:

Tables, views, and temporary tables

Index, primary key, foreign key

Default Value and rule

Stored Procedures, triggers, etc.