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What are the DBMS languages? Briefly explain?
Data Definition language (DDL):A database schema is specified through a set of definitions expressed through a special language called data definition language. For instance, the subsequent statement in the SQL describes the account table
Create table account (account_number char(10), balance integer)
Execution of the above DDL statement creates the account table. DDL permits a user to specify storage structure and access techniques used through the database system as well as specify certain consistency constraints such as balance of an account should on fall below Rs1000.
Data Manipulation language (DML): A data-manipulation language (DML) is a language which enables users to access or manipulate data as organized through the appropriate data model.
There are basically two types:
1) Procedural DMLs needs a user to specify what data are required and how to get those data. 2) Declarative DMLs (also referred to as nonprocedural DMLs) need a user to specify what data are required without specifying how to get those data.
UNION If R1 and R2 are two union compatible relations then R3 = R1 ∪ R2 is the relation having tuples that are either in R1 or in R2 or in both. In case, R3 will have tuples
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The Enhanced Entity Relationship Diagram (ERD) produced with a drawing or case tool. Your EERD must use a ''standard'' notation style such as Crows Foot or Chen. Please note that t
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