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Alter session set current_schema=my_new_schema;
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How can you determine current oracle schema?
select sys_context( 'userenv', 'current_schema' ) from dual;
What do you mean by logical schema in database?
tablespace,segment,extent,oracle blocks.. are the logical schema of a database
Why must create user in oracle todo your work in oracle?
A user in Oracle corresponds to a schema. Objects, such as table and indexes, must exist within a schema. Without creating a user/schema, use of the database will be limited to the built-in schemas and objects, such as the one-row DUAL table and standard PL/SQL packages.
Difference between user and schema oracle?
The both words user and schema are interchangeble,thats why most people get confusion on this words.Below i explained the difference between them--UserUser is a account to connect database(Server). we can create user by using CREATE USER user_name IDENTIFIED BY password.--SchemaActually Oracle Database contain logical and physical strucutre to process the data.The Schema Also Logical Structure to process the data in Database(Memory Component). Its Created automatically by oracle when user created.It Contains All Objects created by the user associated to that schema.For Example if i created a user with name santhosh then oracle createts a schema called santhosh,oracle stores all objects created by user santhosh in santhosh schema.We can create schema by CREATE SCHEMA statement ,but Oracle Automatically create a user for that schema.We can Drop the schema by using DROP SCHEMA schema_name RESTRICT statement but it can not delete scehema contains objects,so to drop schema it must be empty.here the restrict word forcely specify that schema with out objects.If we try to drop a user contain objects in his schema we must specify CASCADE word because oracle does not allow you to delete user contain objects. DROP USER user_name CASCADE so oracle deletes the objects in schema and then it drops the user automatically,Objects refered to this schema objects from other schema like views and private synonyms goes to invalid state.
Is schema a logical structure or physical structure in oracle database?
the schema can be termed either conceptual or logical or physical. But mostly speaking, the term schema is used to refer to a logical structure.
What is a database schema?
A database schema is described in a formal language supported by the database management system (DBMS). In a relational database, the schema defines the tables, the fields in each table, and the relationships between fields and tables. Schemas are generally stored in a data dictionary. Although a schema is defined in text database language, the term is often used to refer to a graphical depiction of the database structure Levels of database schema 1. Conceptual schema, a map of concepts and their relationships 2. Logical schema, a map of entities and their attributes and relations 3. Physical schema, a particular implementation of a logical schema 4. Schema object, Oracle database object 5. Schema is the over all structure of the database
What data is independent?
Data independence is the ability to change the schema at one level of the database system without having to change the schema at the other levels.
What is the difference between schema and database?
Database schema are the logical structure of entities (tables or object classes) and their relationships (keys, or object associations) in a database. Schema can exist at different levels of abstraction (see: en.wikipedia.org/wiki/Database_schema). Schema themselves may or may not exist as such in a database. In general schema at the higher levels of abstraction are design models that are captured in printed documents, and authored by business analysts and database designers, rather than created by database programmers and stored in the database itself. But in some types of databases, schema at any level of abstaction can be realized physically. In Oracle databases, schema can be realized as schema objects, which are a part of an Oracle database. These schema objects may represent a human user's conceptual model of the knowledge captured in an enterprise database. Thus defined, there can be many schema that can be associated with one physical database. In other kinds of relational database, an abstract user's schema can be represented by logically linked metadata, views, and stored procedures assocated with a user class. In object-oriented databases, especially those based on the highly self-referential language Smalltalk (e.g. Gemstone/S), schema are realized as "physical" objects in the database as a matter of course, as well as in the logical models captured in design documents. The schema objects in such databases are, in essence, the classes comprising the infrastructure of the database or application. Oracle-style user schema are readily created; these would be realized as user interface orchestrator classes.
What is star flake schema?
A starflake schema is a combination of a star schema and a snowflake schema. Starflake schemas are snowflake schemas where only some of the dimension tables have been denormalized. hardkingofflirt@gmail.com
What is schema and sub-schema?
The schema is the physical arrangement of the data as it appears in the DBMS. The subschema is the logical view of the data as it appears to the application program.
What Logical data independence and physical data independence?
Logical Data Independence : The ability to change the logical schema without changing the external schema or application programs is called as Logical Data Independence.Physical Data Independence : The ability to change the physical schema without changing the logical schema is called as Physical Data Independence.Logical Data Independence :being able to maintain change at external layer without having to make any change at the concept.Physical Data Independence : we want to be able to make any change on the conceptual level to deal without any change at the physical
Explain the three schema architecture of DBMS?
Physical schema,logical schema and sub schemas
