Related Questions. Define the following terms: data model, database schema, database state, internal schema, conceptual schema, external schema, data independence, DDL, DML, SDL, VDL, query language, host language, data sublanguage, database utility, catalog, Describe each of the following: external schema, logical schema, internal schema. Distinguish between logical and physical data independence, and give examples Define the following terms: relation schema, relational database schema, domain, relation instance, relation cardinality, and relation degree.
How many distinct tuples are in a relation instance with cardinality 22? Does the relational model, as seen Cite some examples of integrity constraints that you think should hold on the database shown in Figure 1.
Define the following terms: data model, database schema, database state, internal schema, conceptual schema, external schema, data Create an Account and Get the Solution.
Physical data independence is when the physical schema is altered without having the need to rewrite application programs for the alteration. Logical data independence is the ability to modify the logical schema without having to rewrite the application program.
Also, what do you mean by logical data independence? Logical data independence is the one which has power Ability to change logical schema without changing external schema or application. Logical data independence in any database applications relates to views where we can only view the data rather than modifying data. Example: Adding or removing.
Physical data independence deals with hiding the details of the storage structure from user applications. Logical data independence : The ability to change the Conceptual Logical schema without changing the External schema User View is called logical data independence. Logical data independence is one of the three levels of abstraction provided by DBMS.
Logical data independence indicates that the application program or the external schema is independent of the conceptual schema or the structure of the data. Asked by: Pekka Treasach asked in category: General Last Updated: 5th June, What is data independence explain the difference between physical and logical data independence?
Explain the difference between physical and logical data independence? In Logical Data Independence the logical schema is modified without rewriting the application programs whereas in Physical Data Independence the physical schema is changed without rewriting the application programs.
What is the importance of data independence? The physical level describes how data is actually stored in the database. In the lowest level, this data is stored in the external hard drives in the form of bits and at a little high level, it can be said that the data is stored in files and folders. What four main types of actions involve databases? Briefly discuss each. Database Administration. What is the difference between data dependence and data independence?
Applications implemented in pre-relational database systems are data-dependent, meaning that both the physical representation of the data and the methods of accessing it are built directly into the application code. The main objective of relational DBMSs is data independence.
How do views support logical data independence? Logical data independence. Views can shield users from changes in the structure of the real tables if such changes become necessary. Unfortunately, views provide only partial logical independence. What are five main functions of a database administrator? The role may include capacity planning, installation, configuration, database design, migration, performance monitoring, security, troubleshooting, as well as backup and data recovery.
Relational algebra is a procedural language and Relational calculus is non-procedural language. In relational algebra user has to specify, what is required, and what the steps to obtain the required output are whereas in relational calculus user has to specify what is needed but does not have to specify how to obtain the result.
Both, relational calculus and relational algebra are formal language. They are the basis on which other, higher level data manipulation languages for relational calculus. Relational algebra have operators like join, union, intersection, division, projection, selection etc.
Expressive power of both relational algebra and relational calculus is equivalent i. Relational algebra is relatively easier to manipulate than relational calculus.
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