DBMS Flashcards
When data is accessed by multiple systems/programs simultaneously. So database manager should ensure that there is no flaw in the data during this concurrent access of data. This management system is termed as _______________________, whose job is to manage the concurrent access to the data.
Transaction and Concurrency control system
Language which is used to work on the database data is _________
Structured Query Language [SQL]
We represent databases pictorially using ____________
E-R diagram [Entity-Relationship diagram]
The retrieving of data stored or recording of data should be fast and therefore, the database is stored in the form of _____
B-Trees and B+ Trees
The Mathmatical model which talks about how to store data in tables is called ___________
Relational Model
SQL is a query lanuage based on ____________ and is used to add,delete,modify,search,retrieve data from the atabase.
relational model
What is a relation?
Reation refers to a table.Table is a set of rows and columns
What are attributes?
Attributes are nothing but the columns in relational database. Attribues are also called as fields.
Attributes are also called as _____________ in table
Fields
Tuples
Rows in a table[relational databse] are called as tuples. They are also known as records.
Tuples are also called as?
Record
In a relation there should not be two same tuples True or False
True
What is an instance in DBMS?
It is a set of tuples/rows along with the table structure
Key
it is he minimum number/set of attributes/columns to uniquely identify a row/tuple.
Simple key
Key with only one attribute/column.
Compound key
Key with multiple attributes/columns
Candidate key
Set of all unique keys is called as Candidate key
Primary key
PRIMARY KEY in DBMS is a column or group of columns in a table that uniquely identify every row in that table. The Primary Key can’t be a duplicate meaning the same value can’t appear more than once in the table. A table cannot have more than one primary key.
