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Explain the conventions for displaying an ER schema as an ER diagram?
An E-R Diagram scheme might describe certain constraints to that the contents of a database must conform.
Mapping Cardinalities: Express the number of entities to that another entity can be related through a relationship. For binary relationship sets among entity sets A and B, the mapping cardinality must be one of:
1. One-to-one: An entity in A is related along with at most one entity in B, and an entity in B is related with at most one entity in A. 2. One-to-many: An entity in A is related along with any number in B. An entity in B is related with at most one entity in A. 3. Many-to-one: An entity in A is related with at most one entity in B. An entity in B is associated with any number in A. 4. Many-to-many: Entities in A and B are related along with any number from each other.
The suitable mapping cardinality for a particular relationship set depends on the real world being modeled. Cardinality ratios for binary relationships are represented on ER diagram through displaying 1,M, N etc. on the diamonds.
Existence Dependencies: if the existence of entity X depends on the existence of entity Y, then X is said to be existence dependent on Y.
Critically evaluate the bulleted list of information-related items in this case study. How are each contradictory to the notion of being an information-literate knowledge worker?
List some instances of collection types? a) sets b) arrays c) multisets
Locks: Serialisabilty is just a test whether a given interleaved schedule is ok or has a concurrency related trouble. Though, it does not make sure that the interleaved concurrent
What is a transaction ? The Transaction is a unit of data processing. For instance, many of the transactions at a bank may be withdrawal or deposit of money; transfer of money f
Consider the subsequent relations RENTER(rno, fname, lname, address, tel_no, pref_type, max_rent) VIEWING(rno, pno, date, comment) PROPERTY_FOR_RENT( pno, street, area ,city,
Define Cascading rollback The phenomenon where a single transaction failure leads to a series of transaction rollbacks is known as Cascading rollback.
What is theta join explain? Theta Join - The theta join operation is an extension to the natural-join operation which permits us to merge selection and a Cartesian
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
what are the states of transaction?
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