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Database Administrator and Different Terms used in Database Creation
Database administrator (DBA)
A database administrator (DBA) is a person or group of persons who are the central control over data and the programs comprising the database system. The main function or responsibilities of a Database administrator (DBA) are:
- Schema definition by writing a set of definitions.
- Deciding the information contents of the database.
- Storage structure and across methods find.
- Intermediator between user and application programmer.
- Ensures the security of the system restricting unauthorized access.
- Maintaining data dictionary.
- Ensuring safe modification for data access.
- Granting of authorization for data access.
- Ensuring data integrity.
- Maintaining data backup and recovery.
Attributes of a Database administrator (DBA)
We know that DBA is a person who is responsible for the maintaining overall DBMS system. A DBA should have the following key attributes/ characteristics.
- Sound knowledge of database design.
- Knowledge of the operating system in which currently the database server is running.
- Knowledge of structure query language (SQL).
- Knowledge of centralized vs distributed database systems.
- Knowledge of database server.
Different terms used in database creation
Data abstraction
Data abstraction is the reduction of a particular body of data to a simplified representation of the whole. Abstraction, in general, is the process of taking away or removing characteristics from something in order to reduce them to a set of essential characteristics. There is different view level of data abstraction.
- Physical level: This is the lowest level of data abstraction which describes how the data are actually stored. In this level of data abstraction, low-level data structures are described in detail.
- Logical level: This is the next level or middle level of data abstraction which describes what type of data is stored in the database and what relationship exists among those data.
- View level: This is the highest or topmost level of data abstraction which describes one part of the entire database. The users interact with the system through the view level.
Data Security
Data security is the process of making and ensuring the data is safe from being lost, damaged, pirated, or unauthorized access. Data are the most valuable things and resources of any organization or user so must be kept safe always. The different levels of data security are:
- Physical level: This is a type of data security in which data and the computer system are kept secure physically, against armed, theft, or other external problems. Physical security also consists of regular maintenance, insurance, protection from fire, dust, smoke, etc.
- Human-level: Human-level security is concerned with the related database users. The database users must be authorized and relevant in order to use and process the data carefully. The data privacy of users is also a factor that may damage the database.
- Operating system level: This is another security level that is adopted to make the database secure by the policy of operating system at different levels. Today there are many options of security provided by the operating systems such as administrators, users, guests, etc.
- Network-level: The network level is another important level of data security that can be applied to the networking system by the physical layer of the network since all the databases are connected through the network.
- Logical level: The logical level is another important level of data security in which data can be protected logically by controlling the data from being opened, modified, or lost by unauthorized users. At this level, data security can be maintained by using the backup system, keeping passwords, applying defragmentation, Scandisk, etc.
The primary key
The primary key is a unique identifier in a master table that uniquely identified the record in the table. The primary key doesn’t accept duplicate or null values. The table with the primary key is known as the master table. When a new record is added to the table, MS-Access checks to ensure that there is no other record with the same value in the primary key field. If the data is a duplicate, Access will display a message indicating that duplicate values exist and will not allow the record to be saved. For example, in the exam table, symbol no. is the primary key that is unique and distinguishes one student from another.
The primary key field cannot be left blank when a new record is added to the table s it is the field that is checked and used for sorting. Access will not allow the record to be saved. When you select to create a new table by adding records in the Datasheet View, a new feature in Access 2007 automatically creates a field named ID that is defined as the primary key. The data type assigned to ID is the Autonumber type, assigning a sequential number with each new record.
Uses of Primary Key
The following are the major uses and importance of the primary key.
- To identify each record uniquely.
- To reduce data redundancy (duplication).
- To set the relationship among tables.
- Not to leave any field blank.
Foreign Key
The foreign key is a primary key field in a linked table whose value matches another table. In another word, it is a linking pin between two tables.
Composite Key
A composite key is a group of fields with the primary key. Thus, a table having more than one field with the primary key field is known as a composite key.
Relationship
A relationship, in the context of databases, is a situation that exists between two relational database tables when one table has a foreign key that references the primary key of the other table. Relationships allow relational databases to split and store data in different tables while linking disparate data items. Types of relationships.
There are four relationships in the database.
- One to One
- One to Many
- Many to One
- Many to Many
Data integrity
Data integrity in the database is the term that refers to the accuracy, consistency, and completeness of data. Data integrity is very important to make a database error-free. Data integrity also refers to maintaining and assuring the accuracy and consistency of data over its entire life-cycle and is a critical aspect of the design, implementation, and usage of any system which stores, processes, or retrieves data. The term data integrity is broad in scope and many have widely different meanings depending on the specific context – even under the same general umbrella of computing. This article provides only a broad overview of some of the different types and concerns of data integrity.
The following are the major types of data integrity.
- User-defined integrity
- Entity integrity
- Domain integrity
- Referential integrity.
