20 Questions
What does RDMS stand for?
Relational Data Management System
How are data stored in RDMS?
As rows and columns
What is the primary key used for in RDMS?
Exclusively find out the rows
How is RDMS different from DBMS?
RDMS speaks about relations between entities, while DBMS does not
What is the primary purpose of a table in a relational database?
To store a collection of related data entries
What is a field in the context of a table in a relational database?
A column in a table designed to maintain specific information about every record
In the context of a relational database, what is a record or a row?
Each individual entry that exists in a table
What is the role of a column in the context of a table in a relational database?
To contain all information associated with a specific field in a table
What does a NULL value represent in the context of a table in a relational database?
A value in a field that appears to be blank
What is the purpose of an RDBMS (Relational Database Management System)?
To manage databases based on the relational model introduced by E.F.Codd
What does the UNIQUE constraint ensure in SQL?
All values in a column are different
Which type of constraint ensures that a column cannot have a NULL value in SQL?
DEFAULT Constraint
What is the primary purpose of a PRIMARY Key in SQL?
Uniquely identifies each row/record in a database table
In SQL, what does the FOREIGN Key do?
Uniquely identifies a row/record in any another database table
What is the primary purpose of a primary key in a table within a relational database?
To enforce the uniqueness of each row
Which type of integrity ensures that rows cannot be deleted if they are used by other records?
Referential Integrity
What is the common data type for a primary key column in MySQL?
INTEGER
Which constraint can be used to ensure the uniqueness of values in a column or group of columns in a table?
UNIQUE constraint
What is the purpose of the AUTO_INCREMENT attribute for a primary key column?
It generates sequential integers for the column
Which constraint ensures that a column cannot contain NULL values?
NOT NULL constraint
Study Notes
Relational Database Management System (RDBMS)
- RDMS stands for Relational Database Management System
- In RDMS, data is stored in tables with rows and columns, where each row represents a single record and each column represents a field or attribute of that record
Primary Key
- A primary key is a column or set of columns in a table that uniquely identifies each record
- The primary key is used to ensure that each record in a table is unique
- The primary purpose of a primary key is to identify each record in a table
Constraints
- The UNIQUE constraint ensures that all values in a column or set of columns are unique
- The NOT NULL constraint ensures that a column cannot have a NULL value
- The PRIMARY KEY constraint ensures that a column or set of columns uniquely identifies each record and cannot be NULL
Foreign Key
- A foreign key is a column or set of columns in a table that refers to the primary key of another table
- The foreign key establishes a relationship between two tables
Data Integrity
- Entity integrity ensures that each record in a table is unique
- Referential integrity ensures that rows cannot be deleted if they are used by other records
Data Types
- The common data type for a primary key column in MySQL is INT (integer)
Auto-Increment
- The AUTO_INCREMENT attribute is used to automatically generate a unique integer for a primary key column when a new record is inserted
Constraints in SQL
- The PRIMARY KEY constraint ensures that a column or set of columns uniquely identifies each record and cannot be NULL
- The UNIQUE constraint ensures that all values in a column or set of columns are unique
- The NOT NULL constraint ensures that a column cannot have a NULL value
Learn about RDMS (Relational Database Management System) and its basic features. Understand how information is stored in tables and how multiple users can access it simultaneously.
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