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The ALTER command is a DDL command that can be used to change the structure of existing tables in the database by adding, modifying, renaming, or removing columns and constraints. Using the ALTER command, you can add columns, rename columns, delete columns, or change the data type of columns. ALTER Command: Syntax Adding a Column: […]
March 14, 2023 | DBMS | No comments
SQL Data Types are an important component of the attributes present in the tables, as well as the queries used to retrieve data from those tables. SQL data types define attributes based on the categories to which they belong. Data types are mainly classified into three categories for every database. String Data types Numeric Data […]
March 12, 2023 | DBMS | No comments
The SQL CREATE command is a type of DDL command that is primarily used for creating databases and tables. To create databases or tables with the desired structure, the CREATE command has a specific syntax that must be followed.Before we can perform any other functions, we must first create a database, which is the first […]
March 12, 2023 | DBMS | No comments
A programming language called SQL (Structured Query Language) was created specifically for managing and modifying relational databases. It offers a common syntax for entering queries and making changes to data in databases. SQL was the first commercial language introduced for E.F Codd’s Relational model of a database. Note: The programming language SQL was created specifically for managing […]
March 12, 2023 | DBMS | No comments
What is 5NF? The fifth normal form, or 5NF, is also called the project-join normal form. If a relation is in 4NF and does not have lossless decomposition into smaller tables, it is in Fifth Normal Form (5NF). If redundancy is avoided, 5NF is satisfied when all tables are divided into as many tables as […]
March 12, 2023 | DBMS | No comments
What is 4NF? A level of database normalisation known as the fourth normal form (4NF) is one in which a candidate key is the only non-trivial multivalued dependency. It advances the Boyce-Codd Normal Form and the first three normal forms (1NF, 2NF, and 3NF) (BCNF). It specifies that a database shall not have more than […]
March 3, 2023 | DBMS | No comments
What is BCNF? The Boyce-Codd Normal Form also referred to as the 3.5 Normal Form, is an extension of the third normal form. In relational database design, the Boyce-Codd Normal Form (BCNF) is a stricter normal form than the third normal form (3NF). Rules for BCNF: Boyce-Codd Normal Form (BCNF) rules are as follows: Every […]
March 1, 2023 | DBMS | No comments
What is Third Normal Form? The third step in Normalization is 3NF. For a table to be in third normal form, it needs to satisfy the following conditions: For every non-trivial function dependency X → Y. X is a super key. Y is a prime attribute, i.e., each element of Y is part of some […]
February 28, 2023 | DBMS | No comments
What is 2NF? The second step in Normalization is 2NF. A table must meet two requirements to be in the second normal form: The relation must be in the 1NF. In the second normal form, all non-key attributes are entirely functionally dependent on the primary key Let’s see, what we mean by dependency. What are […]
February 28, 2023 | DBMS | No comments
What is Database Normalization? A database design technique called normalization reduces data duplication and gets rid of undesirable traits like Insertion, Update, and Deletion Anomalies. Using relationships, normalization rules break up larger tables into smaller tables. SQL normalization serves the dual purpose of removing unnecessary (repetitive) data and ensuring logical data storage. Why is normalization […]
February 25, 2023 | DBMS | No comments