Week1.pptx

Database Systems Faculty: Joseph Agyei, PhD Stephane Nwolley Jnr., PhD Objective Some common uses of database systems. The characteristics of file-based systems. The problems with the file-based approach. The meaning of the term ‘database’. The meaning of the term ‘database management...

Database Systems Faculty: Joseph Agyei, PhD Stephane Nwolley Jnr., PhD Objective Some common uses of database systems. The characteristics of file-based systems. The problems with the file-based approach. The meaning of the term ‘database’. The meaning of the term ‘database management system’ (DBMS). The typical functions of a DBMS. The personnel involved in the DBMS environment. The advantages and disadvantages of DBMSs.  Introduction Database – Loosely speaking, a database is a collection of related data. Common Uses of Database Retail sector-department stores, food outlets, Social Media –User profile, Comments, likes, images Service Industry - Accounting practices, marketing firms etc. Health industry - patient records, hospitals, dental surgery, doctors surgery.  Introduction Imagine that you own a small business, say a video rental shop. What sort of information, that is data, would you have to keep? Current stock: – Levels of current stock, titles of movies and the manufacturers are just some examples of information stored. Customer: – Names, Addresses, Phone, Fax etc. are some of the details stored about the customer. Staff: – Similar details to customer, plus work commencement date, DOB as well. Loans: – Current, overdue, past, holds etc. Suppliers: – videos, snacks, stationery etc. Accounts: – Income, expenses, debtors, creditors etc.  Introduction A Step back in time: File based approach to data management  Introduction File based Approach: example  Introduction File based Approach to data management  Introduction File based Approach search  How many Students have paid their fees who are in computer science class?  Total number of Student who had “A” and did calculus  Students who fell ill from the CS department who have paid their fees  The Database Data Database A shared collection of logically related data, and a description of this data, designed to meet the information needs of an organization. DBMS A software system that enables users to define, create, maintain, and control access to the database. Data Definition Language (DDL) & Data Manipulation Language (DML) Database Systems (Database + DBMS)  The Database See you in next class A Simplified database system environment  Database Management System Database Management System (DBMS) provides…. … efficient, reliable, convenient, and safe multi-user storage of and access to massive amounts of persistent data.  Database Management System  Massive - terabyte  Persistent – it outlives the program that runs on them  Safe – hardware and software in terms of failures  Multi-user – concurrency control  Convenient – declarative to find algorithms  Efficient – thousands of query per seconds  Reliable – 99.999999%  Database Management System Allow Students to lead this discussion Main Characteristics of the Database Approach The main characteristics of the database approach versus the file-processing approach are the following: 1. Self-describing nature of a database system: A fundamental characteristic of the database approach is that the database system contains not only the database itself but also a complete definition or description of the database structure and constraints. A DBMS catalog stores the description of the database. The description is called meta-data(author, date created, etc)). This allows the DBMS software to work with different databases. Main Characteristics of the Database Approach 2. Support of multiple views of the data: Each user may see a different view of the database, which describes only the data of interest to that user. 3. Sharing of data and multiuser transaction processing : Allowing multiple users to access the database at the same time. The DBMS must include concurrency control software to ensure that several users trying to update the same data do so in a controlled manner so that the result of the updates is correct. For example, when several reservation agents try to assign a seat on an airline flight, the DBMS should ensure that each seat can be accessed by only one agent at a time for assignment to a passenger.  Database Users Actors on the scene – Database administrators: responsible for authorizing access to the database, for co-ordinating and monitoring its use, acquiring software, and hardware resources, controlling its use and monitoring efficiency of operations. – Database Designers: responsible to define the content, the structure, the constraints, and functions or transactions against the database. They must communicate with the end-users and understand their needs. – End-users: they use the data for queries, reports and some of them actually update the database content.  Categories of end users Casual : access database occasionally when needed Naïve or Parametric : they make up a large section of the end-user population. – They use previously well-defined functions in the form of “canned transactions” against the database. – Examples are bank-tellers or reservation clerks who do this activity for an entire shift of operations.  Categories of end users Sophisticated : these include business analysts, scientists, engineers, others thoroughly familiar with the system capabilities. Many use tools in the form of software packages that work closely with the stored database. Stand-alone : mostly maintain personal databases using ready-to-use packaged applications. An example is a tax program user that creates his or her own internal database. Historical Development of Database Technology Early Database Applications: The Hierarchical and Network Models were introduced in mid 1960’s and dominated during the seventies. A bulk of the worldwide database processing still occurs using these models. Relational Model based Systems: The model that was originally introduced in 1970 was heavily researched and experimented with in IBM and the universities. Relational DBMS Products emerged in the 1980’s. Advantages & Disadvantage of DBMS Advantages & Disadvantage of DBMS  Recap Some common uses of database systems. The characteristics of file-based systems. The problems with the file-based approach. The meaning of the term ‘database’. The meaning of the term ‘database management system’ (DBMS). The typical functions of a DBMS. The personnel involved in the DBMS environment. The advantages and disadvantages of DBMSs.  Recap https://www.upwork.com/hiring/data/sql-vs- nosql-databases-whats-the-difference/