Schema comparison of MySQL, SQL Server, and Oracle Database

In the Database system class, the teacher introduced two types of databases: Oracle Database and SQL Server. They also talked about the differences between Schema and SQL Server, here, I also want to add the difference between the MySQL mode and the MySQL mode that I usually use.

The schema is equivalent to the namespace in the database system. A schema can contain multiple objects, such as basic tables, views, and indexes. To access an object in a certain mode, you must specify the Mode name. Object name.

Oracle Database

When logging on to the Oracle Database client, you must provide the user name, password, and Database name. After logging on, you must provide the user name to query the data in the table. the table name can be used to query a user's data table. If you are using your own table, you can omit the user name and directly provide the table name. Here, each user can create his/her own table. The Mode name is his/her username. When a user is created in Oracle Database, he/she creates a mode with the same name. Therefore, he/she cannot create a mode, you cannot delete the mode. To do this, create and delete users.

SQL Server

When logging on to the SQL Server client tool, you do not need to specify a database. You only need to provide the user name and password. You can log on to the entire database Server to view all databases and tables. It has several built-in modes. One of the default modes is dbo. If you do not specify the mode when creating a table, it belongs to dbo mode.

MySQL

When logging on to the MySQL client tool, you do not need to specify a database. After logging on with the user name and password, you can see all the databases and tables in the database system. The SCHEMA is different from the previous two. The DATABASE name is the SCHEMA name. The create database statement is equivalent to the create schema statement. If the DATABASE is not specified when accessing the table (specified by the use statement ), the database name is used. table name.