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What are the advantages of relational data model?
Advantages• Ease of use - The revision of any information as tables consisting of rows and columns is quite natural and thus even first time users search it attractive.
• Flexibility - Various tables from that information has to be linked and extracted can be simply manipulated through operators such as project and join to provide information in the form in that it is desired.
• Security - Security control and authorization could also be implemented more easily through moving sensitive attributes within a given table into a separate relation along with its own authorization controls. If authorization needs permits, a particular attribute could be joined back along with others to enable full information retrieval.
• Data Independence - Data independence is achieved more simply along with normalization structure used in a relational database than in the more complex tree or network structure. It also frees the users from details of storage structure and access techniques.
• Data Manipulation Language - The possibility of responding to ad-hoc query through means of a language based on relational algebra and relational calculus is simple in the relational database approach. Gives simplicity in the data organization and the availability of reasonably easy to extremely powerful query languages.
What is Index? An index is a physical structure having pointers to the data. Indices are created in an existing table to locate rows more quickly and efficiently. It is possibl
Order by clause By using this rows can be sorted It is used in the last portion of select statement By default it gets ascending order DESC: is used
Define blocks? The database system resides eternally on non-volatile storage, and is into fixed-length storage units known as blocks.
About Attribute inheritance
Designing the fields in the data base The following are the considerations one has to remain in mind while designing the fields in the data base. Coding, compression, en
I have a homework assignment due today by midnight. I need help understanding databasse normalization and determining the type of form violation & how to fix the violation.
Example : Create a sequence named SEQSS that starts at 105, has a step of 1 and can take maximum value as 2000. CREATE SEQUENCE SEQSS START WITH 105 INCREMENT BY 1 MAX VA
Describe the shadow paging technique.
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With the help of an example display how records can be deleted and updated in QBE. (i) Increase Pay_Rate of employees along with the skill of ‘cook' by 10%. (ii) Delete employee
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