First, the database objects:
Schema objects:
The database is a collection of objects of the logical structure, the basic object is a database table;
Other objects include: create add, drop delete, change alter
Synonyms, sequences, view, index
1, synonyms:
①, an alias for an existing object:
Simplifying the SQL statement, hidden object name and owner to provide public access to the object;
②, type:
Private Synonym:
It can only be accessed in its mode, and can not (currently using the user) with the same name as the current mode of the object;
Public synonym:
The database can be accessed by all users. Only an administrator user created.
③, private: synonym (System Log creation)
- - Create a user the CREATE the USER test IDENTIFIED BY 123456; - create a user named test user password is 123456 GRANT the CONNECT, the CREATE SYNONYM the TO test; - - grant permissions (connect to the database, create synonyms - from Alias) GRANT the SELECT ON sCOTT.EMP the TO the Test; - inquiries GRANT dELETE ON sCOTT.EMP the TO the Test; - delete GRANT UPDATE ON sCOTT.EMP the TO the Test; - increasing the SELECT * from scott.emp; the Create synonym Staff for scott.emp; - aliases - increased security
the SELECT * from Staff; - - private synonymous, only who who create access
④, public: public
Sys or system user needs to create
- a sys or system log on, create a public synonym - who can check
the Create public synonym the emps for scott.emp; the SELECT * from the emps;
Modify and delete principle is: Who created who modify, delete