DATABASE SYSTEM DESIGN detail1. DATABASE DESIGN
Database design is a process to determine the contents and arrangement of data required to support a variety of system design.The design of the system occurs at two levels, namely:At the first level, system planning, analysis and design
generally carried out to determine the user's needs. Level design of this database involves tahapfront-end, free from certain database design or database management system (DBMS).On the second level, general design, such as entity relationship diagrams
high level, is transformed (or decomposed) into the detailed design of the database for a particular DBMS that will be used to implement a total system.Three well-known database models are:
hierarchical model Network Model Relational Model
In the past many sellers (vendors) offer Database Management Systems (DBMS) is based on hierarchical models and network models. Relational model is currently dominant. Therefore, almost all database software vendors offer software products Relational Database Management Systems (RDBMS).RDBMS is made to the structure of the three schemes, namely:
External ConceptualInternal
This layer defines the structure of corporate data at the leveldifferent.External schemes define how users access
and see the output of the RDBMS, free from how data is physically stored or accessed.Access and manipulation of this kind carried out by the user by employing procedural language, such as COBOL or query languages, such as Structured Query Language (SQL), a recognized standard language for RDBMS.Konseptualyang scheme defines the relational database model
consists of a set of normalized tables. Conceptual scheme is the design of a database which is the main subject of this chapter.Internal scheme consists of the physical organization of data (eg, sequential,index sequential, direct) in terms of physical structure of data andmethods of accessing the computer's operating system.RELATIONAL DATABASE IS THAT?
Relational model based on mathematical set theory. The structure is defined by Table. In mathematical terms, a table called a Relation. Professional systems often use the term "table" and "relationship" interchangeably.
Each table in the relational model is composed of rows and columns. The column is called attribute. The value for an attribute value must be selected from a group called the Domain. Because many of the same column in the table can be identified on the same domain, then the name attribute is defined for each column. Each attribute name must be unique within a relation. The order left to right of the column is not important. The order of rows is not important. The intersection of a row and column containing a single value.Table properties:1.Duplikasi row are not allowed. To implement these properties,
must have at least one attribute or combination of attributes that uniquely identify each row of the table. Attribute or a combination of several attributes that carry out this task is called Primary Key (Primary Key). Example:
EmployeeWorkingDepartmentN: 1 (Many-To-One)
An entity A can be associated with at most an entity B, but the entity B can be associated with a number of entities in ANomor_Mahasiswa, is the primary key that identifies eachstudent is unique.2.Database relational is the value of Primary Key should not behave duplicate or NIL (NULL, the value is unknown).3.Keterhubungan (relationship) between two tables. If Table R2have a Foreign Key (Foreign Key) that matchwith the primary key of Table R1, then for each valueForeign Key must have a matching value of PrimeryKey, Foreign Key or value must be nil.Using Structures Query Language (SQL)
SQL is the standard database language used to query, manipulate and update the RDBMS. As more organizations decide to consolidate their databases into the area of enterprise systems, knowledge of SQL would be a need for the designers of the database.2. ENTITY RELATIONSHIP DIAGRAM (ERD)Entity Relationship ModelIs a presentation of data by using the Entity andRelationship.Entity Entity is an object that is engaged in the real world Entity set is a collection of similar entities Entity sets can be:- Object physically: Homes, Vehicles, Equipment- Object is a concept: Work, Business, PlanRelationship Relationship is the relationship between one or moreentity.
Composite AttributesAn attribute that consists of several smaller attributethat have a particular meaning.Attribute DerivativesAn attribute is generated from the other attributes.Degrees of relationshipExplaining the number of entities that participate in arelationship.Unary Degree (degrees One)Analysis and Design SystemPage 5
Binary Degree (Degrees Two)Ternary Degree (Three Degrees)Cardinality Ratio ConstraintExplaining limit the number of connectedness with one entityother entity. Type Cardinality Ratio1: 1 (One-To-One)An entity A is associated to an entity B, and aentity B is associated with at most an entity A.
EmployeePropertyVehicle1: N (One-To-Many)An entity A is associated with a number of entity B, but the entityB can be associated at most one entity A.
Database design is a process to determine the contents and arrangement of data required to support a variety of system design.The design of the system occurs at two levels, namely:At the first level, system planning, analysis and design
generally carried out to determine the user's needs. Level design of this database involves tahapfront-end, free from certain database design or database management system (DBMS).On the second level, general design, such as entity relationship diagrams
high level, is transformed (or decomposed) into the detailed design of the database for a particular DBMS that will be used to implement a total system.Three well-known database models are:
hierarchical model Network Model Relational Model
In the past many sellers (vendors) offer Database Management Systems (DBMS) is based on hierarchical models and network models. Relational model is currently dominant. Therefore, almost all database software vendors offer software products Relational Database Management Systems (RDBMS).RDBMS is made to the structure of the three schemes, namely:
External ConceptualInternal
This layer defines the structure of corporate data at the leveldifferent.External schemes define how users access
and see the output of the RDBMS, free from how data is physically stored or accessed.Access and manipulation of this kind carried out by the user by employing procedural language, such as COBOL or query languages, such as Structured Query Language (SQL), a recognized standard language for RDBMS.Konseptualyang scheme defines the relational database model
consists of a set of normalized tables. Conceptual scheme is the design of a database which is the main subject of this chapter.Internal scheme consists of the physical organization of data (eg, sequential,index sequential, direct) in terms of physical structure of data andmethods of accessing the computer's operating system.RELATIONAL DATABASE IS THAT?
Relational model based on mathematical set theory. The structure is defined by Table. In mathematical terms, a table called a Relation. Professional systems often use the term "table" and "relationship" interchangeably.
Each table in the relational model is composed of rows and columns. The column is called attribute. The value for an attribute value must be selected from a group called the Domain. Because many of the same column in the table can be identified on the same domain, then the name attribute is defined for each column. Each attribute name must be unique within a relation. The order left to right of the column is not important. The order of rows is not important. The intersection of a row and column containing a single value.Table properties:1.Duplikasi row are not allowed. To implement these properties,
must have at least one attribute or combination of attributes that uniquely identify each row of the table. Attribute or a combination of several attributes that carry out this task is called Primary Key (Primary Key). Example:
EmployeeWorkingDepartmentN: 1 (Many-To-One)
An entity A can be associated with at most an entity B, but the entity B can be associated with a number of entities in ANomor_Mahasiswa, is the primary key that identifies eachstudent is unique.2.Database relational is the value of Primary Key should not behave duplicate or NIL (NULL, the value is unknown).3.Keterhubungan (relationship) between two tables. If Table R2have a Foreign Key (Foreign Key) that matchwith the primary key of Table R1, then for each valueForeign Key must have a matching value of PrimeryKey, Foreign Key or value must be nil.Using Structures Query Language (SQL)
SQL is the standard database language used to query, manipulate and update the RDBMS. As more organizations decide to consolidate their databases into the area of enterprise systems, knowledge of SQL would be a need for the designers of the database.2. ENTITY RELATIONSHIP DIAGRAM (ERD)Entity Relationship ModelIs a presentation of data by using the Entity andRelationship.Entity Entity is an object that is engaged in the real world Entity set is a collection of similar entities Entity sets can be:- Object physically: Homes, Vehicles, Equipment- Object is a concept: Work, Business, PlanRelationship Relationship is the relationship between one or moreentity.
Composite AttributesAn attribute that consists of several smaller attributethat have a particular meaning.Attribute DerivativesAn attribute is generated from the other attributes.Degrees of relationshipExplaining the number of entities that participate in arelationship.Unary Degree (degrees One)Analysis and Design SystemPage 5
Binary Degree (Degrees Two)Ternary Degree (Three Degrees)Cardinality Ratio ConstraintExplaining limit the number of connectedness with one entityother entity. Type Cardinality Ratio1: 1 (One-To-One)An entity A is associated to an entity B, and aentity B is associated with at most an entity A.
EmployeePropertyVehicle1: N (One-To-Many)An entity A is associated with a number of entity B, but the entityB can be associated at most one entity A.
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