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Description
Flashcards by Aparna Dhirde, updated more than 1 year ago
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Created by Aparna Dhirde
over 4 years ago
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| Question | Answer |
| Database | Collection of interrelated data. |
| File System | It is a container to store data in a computer. |
| Difficulty in Access | Files themselves do not provide any mechanism to retrieve data. |
| Data Redundancy | Redundancy means same data are duplicated in different places |
| Data Inconsistency | Data inconsistency occurs when same data maintained in different places do not match. |
| Data Isolation | Data isolation is a property that determines when and how changes made by one operation become visible to other concurrent users and systems. |
| Data Dependence | Data are stored in a specific format or structure in a file independently. |
| DBMS | Database Management System |
| Examples of open source and commercial DBMS | MySQL, Oracle, PostgreSQL, SQL Server, Microsoft Access, MongoDB. |
| Database Schema | It is the skeleton of the database that represents the structure (table names and their fields/columns), the type of data each column can hold, constraints on the data to be stored (if any), and the relationships among the tables. |
| Data Constraint | certain restrictions or limitations on the type of data that can be inserted in one or more columns of a table. |
| Meta-data or Data Dictionary | The database schema along with various constraints on the data is stored by DBMS in a database catalog or dictionary, called meta-data. A meta-data is data about the data. |
| Database Instance | When we define database structure or schema, state of database is empty i.e. no data entry is there. |
| Query | A query is a request to a database for obtaining information in a desired way. |
| Data Manipulation | Modification of database consists of three operations viz. Insertion, Deletion or Update. |
| Database Engine | Database engine is the underlying component or set of programs used by a DBMS to create database and handle various queries for data retrieval and manipulation. |
| RDBMS | Relational Database Management System |
| ATTRIBUTE | Characteristic or parameters for which data are to be stored in a relation. |
| TUPLE | Each row of data in a relation (table) is called a tuple. |
| DOMAIN | It is a set of values from which an attribute can take a value in each row. |
| DEGREE | The number of attributes in a relation is called the Degree of the relation. |
| CARDINALITY | The number of tuples in a relation is called the Cardinality of the relation. |
| Candidate Key | A super key with no redundant attribute is known as candidate key. |
| Primary key | unique identification of tuples. |
| Foreign key | Primary key of another table |
| Composite Primary key | If no single attribute in a relation is able to uniquely distinguish the tuples, then more than one attribute are taken together as primary key. Such primary key consisting of more than one attribute is called Composite Primary key. |
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