Write a note on relational model.

The relational model in DBMS is an abstract model used to organize and manage the data stored in a database. It stores data in two-dimensional inter-related tables, also known as relations in which each row represents an entity and each column represents the properties of the entity.

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Explain any five relational algebra operators.

SELECT (σ): The SELECT operation is used for selecting a subset of the tuples according to a given selection condition. Sigma(σ)Symbol denotes it. It is used as an expression to choose tuples which meet the selection condition. Select operator selects tuples that satisfy a given predicate. Projection(π) The projection eliminates all attributes of the input relation but those mentioned in the projection list. The projection method defines a relation that contains a vertical subset of Relation. This helps to extract the values of specified attributes to eliminates duplicate values. (pi) symbol is used to choose attributes from a relation. This operator helps you to keep specific columns from a relation and discards the other columns. Rename (ρ) Rename is a unary operation used for renaming attributes of a relation. ρ (a/b)R will rename the attribute ‘b’ of relation by ‘a’. Union operation (υ) UNION is symbolized by ∪ symbol. It includes all tuples that are in tables A or in B. It also el...
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. What is join? Explain the types of join with example.

A JOIN clause is used to combine rows from two or more tables, based on a related column between them Different Types of SQL JOINs Here are the different types of the JOINs in SQL: (INNER) JOIN: Returns records that have matching values in both tables LEFT (OUTER) JOIN: Returns all records from the left table, and the matched records from the right table RIGHT (OUTER) JOIN: Returns all records from the right table, and the matched records from the left table FULL (OUTER) JOIN: Returns all records when there is a match in either left or right table
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Explain database languages

Database Languages are the set of statements, that are used to define and manipulate a database. A Database language has Data Definition Language (DDL), which is used to construct a database & it has Data Manipulation Language (DML), which is used to access a database.
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