External level ->It is the first level of the database architecture that maintains the external view of the database and closed to the user. This level helps to observe data record individually. The user can also manage this structure by controlling the database record. It identifies the fields or column of the database and helps to store of records. the level of abstraction that describes only part of the entire database called view level.
Conceptual level->This level is database architecture describe the different data type of view level. The database administrator defines this storing the values into a database file. The database architecture maintains datatype like char, int etc at this level its concerts with the physical part of database architecture.
Internal level->It is the lowest the level of database architecture that maintains the size of data storage and it used to the physical storage device. This level know as physical level because it helps to store the data on the storage medium like hard disk magnetic tape etc. The database administrator defines the size of particular field where we store the records
It is a term of the system to define the overall architecture of all data item its record type store in a database. The database manages schema definition to define the structure like external level, view and internal. The database schema helps us to manage the database file records and its definition.
It is a term of the database that refers to an application programmer to manage the data record and items for the particular database using subschema. It also refers to logical views of the schema.
The database is managed with a different view like external, internal and conceptual. Any changes at any level may affect other levels of database architecture know as Data independent. The concept of data independence proves beneficial in particular context.
Physical data independence->It refers to the ability to change at any part of the physical level in database architecture without affecting and conceptual level of the database schema. The application a program remain the same schema at the physical level.
Logical independence->It refers to availability to modify at the conceptual level of schema without any changes at the external level. It is more difficult to manage logical data independence because the application program is mostly dependent on the logical structure of the database. The abstract datatype is used in programming independence concept.
A data model help to manage the data structure and describe the data, relationship consistency etc database model, classify into different part as following
Conceptual data model->It is a database model that we in describing and the conceptual level and also external level. In this model of the database with defining the relationship between the components using entity-relationship model. It also knows as object base database model.
Physical data model->The database describes the lowest part of architecture to manage the physical part of database design, this model manages the physical part to control the data storage. It also represents the physical component and implements the database at the system level.
Logical data model->It is the model that describes the conceptual and view level of database architecture. In this model, we select database type like hierarchical network RDBMS this model basically use to manage the records and its format. The database administratory define the file processing and database application for data maintenance at this level.
It is a process to describe the schema of the database. The data mapping manage the data dictionary that contains complete details of the database structure. The user refers only architecture and the conceptual schema also build with this level. The process to covert a request form external view at the result of view level is described as mapping.
External conceptual mapping->In this mapping, we define the correspondence between the external view and the conceptual view. In DBMS the conceptual view level corresponds to the object on external level of the user. If change is made either external view or conceptual view the mapping must change.
Conceptual internal mapping->It is the mapping process that defines the correspondence between conceptual view the internal view. The database stored on the physical device like magnetic tape, compact disk etc It describes how conceptual record store and retrieved from the data storage device. This mapping also maintains the path of data storage DBMS maintains a three-level structure that concerned with schema mapping process help to manage the data and its processing.
It is the logical and physical structure of data storage in a database.
Requiring collection and analysis->It is the process of the database design that allows collecting the required data and analysis them. It is the first step of database design that collects details of the requirement to particular information through user and also solves the problem if they face.
Conceptual database design->After collecting and analyzing the data for database design we maintain conceptual schema in the base of particular database management system. The conceptual schema maintains the description of data requirement of the user and includes a detail description of data requirement of the user and the entity type, relationship, and limitation. In this stop, we also maintain the relationship between components using ER-model.
Physical database design->In this phase of database design, we maintain data storage device as a physical and internal term of database architecture. It manages the physical path of data storage database that help that help access the records.
Role of database design(DBA)
DBA stands for a database administrator. It is implemented by a person or group of person to maintain the database detail and process record under the supervision of knowledgeable person DBA.
There are the following role of DBA
Schema definition-> The database the administer manage the schema is created by a set of definition which is translated by data definition language(DDL) compiler. It also maintains the data dictionary.
Storage structure definition-> The database use appropriate structure to manage the data storage and excess. This method use set of definition which is translated by the storage and definition language compiler.
Granting permission definition->DBA Database administrator and other processing of the table. DBA is responsible to check the user authentication and provide permission for the data table.
Routine maintainance-> The Database Administrator is responsible for defining the procedure to recover data from the backup area when the data get a failure due to a particular reason. DBA maintain the data as a backup in daily routine.
Maintaining integrity-> DBA ensure that appropriate resources are taken to maintain the limitation for the database. The database provides it different integrity constraints for managing the structure and data.