ANALISISA & PERANCANGAN SISTEM

Transkripsi

1 ANALISISA & PERANCANGAN SISTEM Analisis dan Permodelan Data (Data Modeling and Analysis) Mulyadi, S.Kom, M.S.I

2 DATA MODELING Data modeling teknik mengorganisasikan dan mendokumentasikan data (disebut pemodelan DB) Entity relationship diagram (ERD) pemodelan data menggunakan beberapa notasi utk menggambarkan data dengan menggunakan ENTITY dan RELATIONSHIP atau hubungan diantaranya.

3 Sample Entity Relationship Diagram (ERD)

4 Data Modeling Concepts: Entity Entity menunjukkan kelas dari orang, tempat, benda, kejadian atau konsep yang diperlukan untuk disimpan. Penamaan menggunakan kata benda tunggal Orang : agency, contractor, customer, department, division, employee, instructor, student, supplier. Tempat : sales region, building, room, branch office, campus. Objek : book, machine, part, product, raw material, software license, software package, tool, vehicle model, vehicle. Peristiwa : aplikasi, penghargaan, pembatalan, kelas, penerbangan, faktur, order, pendaftaran, pembaharuan, permintaan, pemesanan, penjualan, perjalanan. Konsep: account, block of time, bond, course, fund, qualification, stock.

5 Data Modeling Concepts: Attributes Attribute ciri atau karakteristik entity. Disebut juga elemen, sifat atau field Compound attribute terdiri gabungan atribut. Disebut atribut gabungan (composit, Concatenated atau struktur data

6 Data Modeling Concepts: Data Type Data type sifat/ciri dari atribut yang menentukan tipe data yang disimpan dalam database Representative Logical Data Types for Attributes Logical Data Type NUMBER TEXT MEMO DATE TIME YES/NO VALUE SET IMAGE Logical Business Meaning Any number, real or integer. A string of characters, inclusive of numbers. When numbers are included in a TEXT attribute, it means that we do not expect to perform arithmetic or comparisons with those numbers. Same as TEXT but of an indeterminate size. Some business systems require the ability to attach potentially lengthy notes to a give database record. Any date in any format. Any time in any format. An attribute that can assume only one of these two values. A finite set of values. In most cases, a coding scheme would be established (e.g., FR=Freshman, SO=Sophomore, JR=Junior, SR=Senior). Any picture or image.

7 Data Modeling Concepts: Domains Domain sifat dari atribut yang mendefinisikan nilai yang diperkenenkan di dalamnya (nilai yang sah) Default value nilai yang otomatis diberikan (Default) apabila user tidak memberikan keterangan terhadap suatu data

8 Representative Logical Domains for Logical Data Types Data Type Domain Examples NUMBER TEXT For integers, specify the range. For real numbers, specify the range and precision. Maximum size of attribute. Actual values are usually infinite; however, users may specify certain narrative restrictions. {10-99} { } Text(30) DATE Variation on the MMDDYYYY format. MMDDYYYY MMYYYY TIME For AM/PM times: HHMMT For military (24-hour times): HHMM HHMMT HHMM YES/NO {YES, NO} {YES, NO} {ON, OFF} VALUE SET {value#1, value#2, value#n} {table of codes and meanings} {M=Male F=Female}

9 Data Modeling Concepts: Identification Key atribut/gabungan yang memberikan nilai yang unik terhadap isi dari entity (disebut identifier) Concatenated key - sekelompok atribut yang secara unik mengidentifikasi suatu entitas. Candidate key salah satu dari sejumlah kunci yang dapat berfungsi sebagai kunci utama dari entitas. Primary key candidate key yang akan paling sering digunakan untuk secara unik mengidentifikasi entitas. Alternate key candidate key yang tidak digunakan sebagai primary key (secondary key).

10 Data Modeling Concepts: Relationships Relationship hubungan yang ada diantara entity Dinyatakan dengan garis hubung diantara entity tsb Student Is being studied by is enrolled in Curriculum Cardinality minimum/maksimum jml kejadian (occurrence) dari suatu entity mempunyai hubungan dengan lainnya Karena hubungan timbal balik maka kardinalitas haru didefinisikan ke dua arah (bidirectional) bidirectional Student Is being studied by is enrolled in Curriculum

11 Cardinality Notations

12 Relationship

13

14 Data Modeling Concepts: Degree Degree jumlah entity yang terdapat dalam suatu relasi Relasi diantara dua buah entity disebut binary relationship. Relasi antara instance yang berbeda didalam satu entity disebut recursive relationship. Relasi diantara tiga entity disebut 3-ary or ternary relationship.

15 Data Modeling Concepts: Degree Relasi bisa terjadi antara lebih dari 2 entitas dan disebut N- ary relationships. Contoh ERD disamping menggambarkan ternary relationship.

16 Data Modeling Concepts: Degree Associative entity an entity that inherits its primary key from more than one other entity (called parents). Associative Entity Each part of that concatenated key points to one and only one instance of each of the connecting entities.

17 Data Modeling Concepts: Foreign Keys Foreign key PK suatu entity yang digunakan pada entity lain untuk mengidentifikasi isinya A foreign key is a primary key of one entity that is contributed to (duplicated in) another entity to identify instances of a relationship. A foreign key always matches the primary key in the another entity A foreign key may or may not be unique (generally not) The entity with the foreign key is called the child. The entity with the matching primary key is called the parent.

18 Data Modeling Concepts: Foreign Keys Primary Key Student ID Last Name First Name Dorm 2144 Arnold Betty Smith 3122 Taylor John Jones 3843 Simmons Lisa Smith 9844 Macy Bill 2837 Leath Heather Smith 2293 Wrench Tim Jones Primary Key Dorm Smith Jones Residence Director Andrea Fernandez Daniel Abidjan Foreign Key Duplicated from primary key of Major entity (not unique)