1) Access the Oracle database through Navicat, connect to the database to see SYSTEM and mode
User: To access the database, you need to be authenticated as an appropriate user and have relevant permissions to complete a series of actions. The SYS user is always created by default and is not locked. It owns the data dictionary and all its associated objects. The SYSTEM user , Always created by default, and not locked, can access all objects in the database
Schema (schema): a collection of all objects owned by a user. A user who has the permission to create objects and created objects is called owning a certain modeNote: Any user who creates database objects (views, tables, etc.) has a schema starting with the user name and is considered a schema user
2) Generally do not create tables in SYSTEM
3) Capitalization issues
1. Create a user name or table. If double quotation marks are not used, they will be converted to uppercase letters by default, and the password is case sensitive
For example, if you create a typppbd user, it will be displayed as TYPPPBD in Navicat, but it is case-insensitive when accessed. By default, the Oracle database will convert lowercase to uppercase for query
2. The field name of the table is the same processing logic as the table name above
3 If you want to distinguish between upper and lower case, you can distinguish by adding double quotes. In this case, the query also needs to match exactly