Database Design

E-R diagram for prepering greeting cards

Assume that you are creating a database table to hold the information of the Items in the Super market. Write down the data type suitable to hold the following information:

a) Item Number

b) Item Description

c) Unit Price

d) Stock Balance

e) Reorder Level

f) Store Location

A telephone area code is numeric data, but in some cases it may be more appropriate to store it as a text field because many countries quote telephone area codes including the trunk prefix 0. For example, Liverpool, England, is in UK area code 0151. Also, it is sometimes more appropriate in countries that have variable-length area codes to sort them lexically, so that 031, 0321, 0322, 0325, and 033 would appear in that order.

It is a term from computer databases. A relational database can have a one-to-many relationship in its data. For example, if you have a customer order database, one table will contain customer names and another will contain their orders. Each customer will only be listed once, but each customer can make many orders. So one customer can be related to many orders. Incorporating that into a database requires the creation of a one to many relationship.

Hi,

1. DFA cannot use empty string transition and NFS can use empty string transition.

2. It use one machine but it use multiple machine.

3. DFA is one state transition but NFA react according to some symbol.

yes,data should b accurate in database.so that if any time we want to retrive data from database we will be able to see correct data.for example burger king arrange a special menu and pricing for weekends.and if data is not accurate then other branches of burger king will not get this information correctly.and due to this business can flop.

A data model specifies the rules and concepts on how to represent objects, their descriptions and how they relate. As such, the data model gives the definitions of the attributes and entities, specifies the datatypes of attributes and give relationships between entities.

SQLite is an ACID-compliant embedded relational database management system contained in a relatively small (~225 KB[1]) C programming library. The source code for SQLite is in the public domain. Unlike client-server database management systems, the SQLite engine is not a standalone process with which the program communicates. Instead, the SQLite library is linked in and thus becomes an integral part of the program. It can also be called dynamically. The program uses SQLite's functionality through simple function calls, which reduces latency in database access as function calls within a single process are more efficient than inter-process communication. The entire database (definitions, tables, indices, and the data itself) is stored as a single cross-platform file on a host machine. This simple design is achieved by locking the entire database file at the beginning of a transaction. SQLite is embedded into a growing number of popular applications. For example, Mozilla Firefox stores a variety of configuration data, (bookmarks, cookies, etc.), in internally managed SQLite databases. As another example, Google's Android OS for cellphones and other small devices includes SQLite.

This is quite an elemental question. Think about it- what would be termed atomic? One that cannot be divided, as from its Greek definition. Atomic values in a relational database mean that they cannot be further divided, according to domain rules defining that attribute. An attribute is a column in the table that people normally think of as a relational database, and the notion is pretty correct. Domain rules define what data and its type can go into a column, and others are inadmissible. For instance, let's say that the database of a particular bank is organized as a set of tables, that is it is relational in nature, and one particular table lists the details of all account holders with the bank. All these details can reasonably form the attributes of the bank's customers, and can therefore be allowed to represent columns in this table. Suppose we have a column that holds the account numbers of the customers, and the domain rule defines that an entry in this column must necessarily be a non-negative, non-zero, integer. By this rule, 2453536 is an atomic value, whereas No. 10, Bowers Avenue is not, since the latter can be split further, and it also does not satisfy the domain rules.

In the context of relational databases, a foreign key is a referential constraint between two tables.[1] The foreign key identifies a column or a set of columns in one (referencing) table that refers to a column or set of columns in another (referenced) table. The columns in the referencing table must be the primary key or other candidate key in the referenced table. A table may have multiple foreign keys, and each foreign key can have a different referenced table. Each foreign key is enforced independently by the database system. Therefore, cascading relationships between tables can be established using foreign keys. Improper foreign key/primary key relationships or not enforcing those relationships are often the source of many database and data modeling problems.

TPS refers to the number of database transactions made per second. MIS or management information system gather relevant data that are from inside and outside of an organization which are then stored in a database. The DSS or decision support system typically gathers inventory data which are organized into relational databases for the purposes of timely analysis.

A binary relationship is a type of relationship between the entities, which links to types of entities in it.

Starvation refers to the use of all resources. As an example a poorly constructed database, poor concurrency controls will result in dbms starvation as usage increases. In effect the database subsystem is STARVING for resources because all available resources are being consumed. As a result you will see a severe degrade in performance.

A state diagram is a type of diagram used in computer science and related fields to describe the behavior of systems. State diagrams require that the system described is composed of a finite number of states; sometimes, this is indeed the case, while at other times this is a reasonable abstraction. Many forms of state diagrams exist, which differ slightly and have different semantics.

A database is a collection of data. It should be integrated , consistent , non- redundant , durable and atomic in nature.

Summary is the sister of dictionary. Summary is the sister of dictionary.

We designate one of the candidate key of a relation to be a primary key because that primary key is use for any foreign key references.

Following are the roles of a DBA.

1) Secures data

2) Configures and maintains user profile

3) Assigns previleges for access

4) Maintain database statistics and plans expansions in hardware and software

5) Continuous system development

The qualifier signed or unsigned may be applied to char or any integer. unsigned numbers are always positive or zero, and obey the laws of arithmetic modulo 2n, where n is the number of bits in the type. So, for instance, if charsare 8 bits, unsigned charvariables have values between 0 and 255, while signed charshave values between -128 and 127 (in a two's complement machine.) Whether plain charsare signed or unsigned is machine-dependent, but printable characters are always positive.

The Islamic Empire, they also invented checks.

_____

The previous answer is not true. By the time of Hammurabi's Code, dating to around 1760 BCE, banking was well enough developed to justify laws governing banking operations. This predates the Islamic empire by almost 2400 years.

This is a part of the scope of work that specifies the fields used in the database tables and offers definitions to these fields; their foreign key relationships, etc.

Black means tense, nervous or over worked Grey means anxieties or strained Amber means mixed emotions Green is average, content Blue means relaxed, calm or at ease Dark blue means very happy White means frustrated or confused Pinkish means fear Red means excited or energised

A- aesthetics

C- cost

C- customer

E- environment

S- size

S-safety

F- function

M- material

The architecture have to be designed before specifications are written, because

• to provide a means of structuring

• the specification and developing different sub-system specifications concurrently

• to allow manufacture of hardware by sub-contractors

• and to provide a model for system costing.

Writing specification for the whole system might bring great complexity and it is difficult to formulate it.

Therefore, it is easier to divide the system into simpler subsystems and define their specification and it will save you the hassle of defining specification and put it into the respective subsystem.

Hence we can concurrently develop subsystems and the specifications to be readily into the implementation stage.

Kajutzs.

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