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Does a relational model provide physical and logical data independence?
Wiki User
∙ 11y ago
Since a user can define a views, logical data independence can achieved by using view definition to hide changes in the conceptual schema.
since the sql user has no knowledge of how the data is physically represented, relying solely on the relation abstraction for querying, physical data independence is also achieved.
Wiki User
∙ 11y ago
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Why do you use Linq over SQL Statements?
The extensibility of the query architecture is used in the LINQ project itself to provide implementations that work over both XML and SQL data. The query operators over XML (LINQ to XML) use an efficient, easy-to-use, in-memory XML facility to provide XPath/XQuery functionality in the host programming language. The query operators over relational data (LINQ to SQL) build on the integration of SQL-based schema definitions into the common language runtime (CLR) type system. This integration provides strong typing over relational data while retaining the expressive power of the relational model and the performance of query evaluation directly in the underlying store.
What is the function of the mitocondria?
Mitochondria provide energy to cells and provide the location for the production of ATP.
Difference between relation and relational schema?
In database design a RELATION is the relationship that you build between two or more tables. As an example lets say you have a Customer table. In this table you have lots of fields FirstName, LastName, Address, City, State, PostalCode, StatusID; etc....... Now StatusID is going to be a numeric value. Lets say that the value is 1 Now you will have a Status Table with multiple fields (ex) StatusID, StatusName, Active, etc..... Now when you display customer information you will not want to show a StatusID as nobody will know what this is. You will want to show the NAME associated with the status. To do this you will create a releationship between StatusID in the Customer table and StatusID in the Status table. In doing so you will provide for faster lookup results, a constraint that does not permit a numeric value in the StatusID field in the customer table that is NOT in the StatusID field of the Status table. THEN... To show correct Results you would write a query something like: SELECT FirstName, LastName, Address, City, State, PostalCode, StatusName FROM Customers as c JOIN Status as s on s.StatusID = c.StatusID A relational Schema is simply a representation of your database highlighting the relationships that you have created throughout.
Can you substitute a 9 x 13 pan for a 2 quart casserole dish?
The answer will depend on the depth of the pan. Since you have not bothered to provide that crucial bit of information, I cannot provide a more useful answer.
What are characteristics of the graph of the linear parent function?
Please don't write "the following" if you don't provide a list.
Explain the difference of internal external and conceptual schemas how are these schema layers related to the concept of logical and physical data independence?
External schemas allows data access to be customized (and authorized) at the level of individual users or groups of users. Conceptual (logical) schemas describes all the data that is actually stored in the database. While there are several views for a given database, there is exactly one conceptual schema to all users. Internal (physical) schemas summarize how the relations described in the conceptual schema are actually stored on disk (or other physical media). External schemas provide logical data independence, while conceptual schemas offer physical data independence.
What technology can you use to provide logical separation and protection between hosts that are on the same physical network?
VLAN
What is High-level nature of hierarchical network and relational database management system?
A Relational Database Management System (RDBMS) is a Database Management System (DBMS) that is based on the relational model as introduced by E. F. Codd. Most popular commercial and open source databases currently in use are based on the relational model.A short definition of an RDBMS may be a DBMS in which data is stored in the form of tables and the relationship among the data is also stored in the form of tables.Network topology is the physical interconnections of the elements (links, nodes, etc.) of a computer network. A local area network (LAN) is one example of a network that exhibits both a physical topology and a logical topology. Any given node in the LAN has one or more links to one or more other nodes in the network and the mapping of these links and nodes in a graph results in a geometrical shape that may be used to describe the physical topology of the network. Likewise, the mapping of the data flows between the nodes in the network determines the logical topology of the network. The physical and logical topologies may or may not be identical in any particular network.Hope this helps!Inclus - We provide individual and corporate training(Inclus.net)Educate, Learn & Serve
What is raid volume?
A logical representation of one or more physical disks configured to provide redundant and/or large storage space for the system.
Did the declaration of independence provide separation of powers?
No. It just told why the colonies wanted independence.
Brief in What is the Difference between physical DFD and logical DFD?
A logical DFD makes it easier to communicate for the employees of an organization, leads to more stable systems, allows for better understanding of the system by analysts, is flexible and easy to maintain, and allows the user to remove redundancies easily. On the other hand, a physical DFD is clear on division between manual and automated processes, gives detailed description of processes, identifies temporary data stores, and adds more controls to make the system more efficient and simple. simply put… 1. Logical DFDs are not concerned about how the system is or will be constructed while Physical DFDs show how the system is or will be constructed. 2. Physical DFDs are more realistic and complex while Logical DFDs are simpler but provide an easier understanding view
What is relational calculus?
Tuple calculus was created by Edgar F. Codd to provide a database-query language. It typically consists of two calculi and domain.
Why the bubble was seen over the wings?
You have failed to provide enough information for any logical answer to be given.
Differentiate logical and physical database?
After all business requirements have been gathered for a proposed database, they must be modeled. Models are created to visually represent the proposed database so that business requirements can easily be associated with database objects to ensure that all requirements have been completely and accurately gathered. Different types of diagrams are typically produced to illustrate the business processes, rules, entities, and organizational units that have been identified. These diagrams often include entity relationship diagrams, process flow diagrams, and server model diagrams. An entity relationship diagram (ERD) represents the entities, or groups of information, and their relationships maintained for a business. Process flow diagrams represent business processes and the flow of data between different processes and entities that have been defined. Server model diagrams represent a detailed picture of the database as being transformed from the business model into a relational database with tables, columns, and constraints. Basically, data modeling serves as a link between business needs and system requirements. Two types of data modeling are as follows: * Logical modeling * Physical modeling If you are going to be working with databases, then it is important to understand the difference between logical and physical modeling, and how they relate to one another. Logical and physical modeling are described in more detail in the following subsections. Logical modeling deals with gathering business requirements and converting those requirements into a model. The logical model revolves around the needs of the business, not the database, although the needs of the business are used to establish the needs of the database. Logical modeling involves gathering information about business processes, business entities (categories of data), and organizational units. After this information is gathered, diagrams and reports are produced including entity relationship diagrams, business process diagrams, and eventually process flow diagrams. The diagrams produced should show the processes and data that exists, as well as the relationships between business processes and data. Logical modeling should accurately render a visual representation of the activities and data relevant to a particular business. The diagrams and documentation generated during logical modeling is used to determine whether the requirements of the business have been completely gathered. Management, developers, and end users alike review these diagrams and documentation to determine if more work is required before physical modeling commences. Typical deliverables of logical modeling include * Entity relationship diagrams An Entity Relationship Diagram is also referred to as an analysis ERD. The point of the initial ERD is to provide the development team with a picture of the different categories of data for the business, as well as how these categories of data are related to one another. * Business process diagrams The process model illustrates all the parent and child processes that are performed by individuals within a company. The process model gives the development team an idea of how data moves within the organization. Because process models illustrate the activities of individuals in the company, the process model can be used to determine how a database application interface is design. * User feedback documentation Physical modeling involves the actual design of a database according to the requirements that were established during logical modeling. Logical modeling mainly involves gathering the requirements of the business, with the latter part of logical modeling directed toward the goals and requirements of the database. Physical modeling deals with the conversion of the logical, or business model, into a relational database model. When physical modeling occurs, objects are being defined at the schema level. A schema is a group of related objects in a database. A database design effort is normally associated with one schema. During physical modeling, objects such as tables and columns are created based on entities and attributes that were defined during logical modeling. Constraints are also defined, including primary keys, foreign keys, other unique keys, and check constraints. Views can be created from database tables to summarize data or to simply provide the user with another perspective of certain data. Other objects such as indexes and snapshots can also be defined during physical modeling. Physical modeling is when all the pieces come together to complete the process of defining a database for a business. Physical modeling is database software specific, meaning that the objects defined during physical modeling can vary depending on the relational database software being used. For example, most relational database systems have variations with the way data types are represented and the way data is stored, although basic data types are conceptually the same among different implementations. Additionally, some database systems have objects that are not available in other database systems. Typical deliverables of physical modeling include the following: * Server model diagrams The server model diagram shows tables, columns, and relationships within a database. * User feedback documentation Database design documentation Understanding the difference between logical and physical modeling will help you build better organized and more effective database systems.
Did the delian league provide security but lessened independence?
true
Why did the modern pan Africa movement grow in the early 1900s?
It was meant to provide unity and independence for blacks throughout Africa
What is the difference between a logical network and physical network?
ll for starters a physical network design well, as the name implies, involves the physical connectivity of each of your hosts on the network. this speaks of the actual physical layout of your network which includes the actual nodes, segments and hosts that appear on the actual layout. on the other hand, a logical network speaks more of data flow in your network. this may be of the different forms of network topology (e.g bus, ring, etc).the difference of the two lies in the way they are presented. one being the real connection layout (physical) while the other is of how data flows within the network (logical).think of it as like cars and roads. the roads represent the physical network wherein each road are interconnected and ends with a destination while the cars represent the logical part of the network wherein they move towards a certain destination within the network. although physical and logical networks vary in meaning still they work hand in hand to better define the same single and structured network.A physical network is different from a logical network. Logical networks are defined at the Network layer by the arrangement of the hierarchical addressing scheme. Physical networks represent the interconnection of devices on a common media. Sometimes, a physical network is also referred to as a network segment
