BMIS Chapter 5

What is the purpose of a database?

A database is a self describing collection of integrated records. A database is composed of: bytes (a character of data), fields, records, table or a file The purpose of a database is to keep track of things. Lists of data involving a single theme can be stored in a spreadsheet; a list that involves data with multiple themes require a database.

What is a DBMS?

DBMS stands for Data Management System. It is a program used to create, process, and administer a database. As with operating systems, almost no organization develops its own DBMS. Instead companies license DB2 from IBM, Microsoft, Oracle, etc. Popular DBMS products are: 1. DB2 -IBM 2. Access and SQL Server- Microsoft 3. Oracle Database- Oracle 4. MySQL- an open sourced DBMS product that is license free for most application. Other DBMS products are available, but these five process the great bulk of databases today. A DMBS and a database are two separate entities. A DBMS is a software program; A database is a collection of tables, relationships, and metadata. Database developers use the DBMS to create tables, relationships, and other structures in the database.

What are primary and foreign keys?

Primary Key- A Key (or primary key) is a column or group of columns that identifies a unique row in a table. Every table must have a key. Sometimes more than one column is needed to form a unique identifier. For example: In a table called city, they key would consist of the combination of columns (city, state) because a Further defining primary key via google- A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records. A primary key's main features are: It must contain a unique value for each row of data. It cannot contain null values. Foreign Key- A term used because such columns are keys, but they are keys of a different (foreign) table than the one in which they reside. Furthering defining Foreign Key: a foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table. In simpler words, the foreign key is defined in a second table, but it refers to the primary key or a unique key in the first table.

Understand what SQL is used for.

SQL- is an international standard language for processing a database. All five of the DBMS products mentioned earlier accept and process SQL statement. You do not need to understand or remember SQL language syntax. Instead, just realize that SQL is an international standard for processing a database. SQL can also be used to create databases and database structures. Furthering Defining: QL is an abbreviation for structured query language, and pronounced either see-kwell or as separate letters. SQL is a standardized query language for requesting information from a database.

What is a data model?

• Database structures can be complex, in some cases very complex. So, before building the database developers construct a logical representation of database data called "Data Model". It describes the data and relationships that will be stored in the database. It is akin to a blueprint. Just as building architects create a blueprint before they start building, so, too database developers create a data model before they start designing the database. Interviews with users lead to database requirements, which are summarized in a data model. Once the users have approved the data model, it is transformed into a database design. That design is then implemented into database structures.

What is normalization?

Normalization- The process of converting a poorly structured table into two or more well-structured tables. A table is such a simple construct that you may wonder how one could possibly be poorly structured. Normalization is the process of organizing data in a database. This includes creating tables and establishing relationships between those tables according to rules designed both to protect the data and to make the database more flexible by eliminating redundancy and inconsistent dependency.

Define what a database is and describe its key elements (forms, reports, queries, and application programs)

Database- As previously stated, a database is a self-describing collection of integrated records. A database application is a collection of forms, reports, queries, and application programs that serves as an intermediary between users and database data. Forms- a form is a window or screen that contains numerous fields, or spaces to enter data. Each field holds a field label so that any user who views the form gets an idea of its contents. A form is more user friendly than generating queries to create tables and insert data into fields. Forms: View data; insert new, update existing, and delete existing data. Reports- the formatted result of database queries and contains useful data for decision-making and analysis. Most good business applications contain a built-in reporting tool; this is simply a front-end interface that calls or runs back-end database queries that are formatted for easy application usage. Reports: Structured presentation of data using sorting, grouping, filtering, and other operations. Queries- A query is a request for data or information from a database table or combination of tables. This data may be generated as results returned by Structured Query Language (SQL) or as pictorials, graphs or complex results, e.g., trend analyses from data-mining tools. Queries: Search based on data values provided by the user. Application Programs- A database application is a computer program whose primary purpose is entering and retrieving information from a computerized database. Early examples of database applications were accounting systems and airline reservations systems, such as SABRE, developed starting in 1957. Application Programs: Provide security, data consistency, and special purpose processing, (ex. Handle out-of-stock situations).

What are entities and attributes?

Entities- An entity is some thing that the users want to track. Examples of entities are: Order, Customer, Salesperson, and Item. Entity names are always singular. "Order" not "Orders" and so on. Attributes- Entities have attributes that describe characteristics of the entity. Example attributes of Order are OrderName, OrderData, SubTotal, Tax, Total, and so forth. Example attributes of Salesperson are: SalespersonsName, Email, Phone, etc. Entities have an identifier, which is an attribute (or group of attributes) whose value is associated with one and only one entity instance. For example, OrderNumber is an identifier of Order because only one Order instance has a given value of OrderNumber.

What are records, tables, files, and fields?

Fields- A byte is a character of data, which in a data base are grouped into fields (or columns), such as Student Name and Student Number. A database table has multiple columns that represent the attributes of an entity. Records- Columns or fields, in turn, are grouped in rows (also called records). The collection of data for all columns (Student Name, Student Number, HW1, HW2, Test Scores, Etc.) are called a row. Groups of columns in a database table. Table/ File- A group of similar rows or records in a database.