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Introduction to Databases A line manager asks, “If data unorganized is like matter unorganized and God created the heavens and earth in six days, how come it takes six months for all these consultants to build a database model for a simple business process?” Introduction to Databases File System Limitations Database Systems History of Databases Pros & Cons of Databases Database Careers File System Limitations Section #1 Separating and Joining Data Duplicating Data Data Dependence Incompatible File Formats Fixed Queries Security Limitations Separating and Isolating Data Files store related data about a subject Joining files lets you answer questions Files only contain information for their primary purpose. Programs resolve complex relationships and formatting between different files. Business reports read multiple files Programmers write reports by joining data from multiple files to create meaningful information. Duplicatiing Data Files systems duplicate data Files maintain their copy of the data Files become data islands with complex organization, and store copies of secondary data from other files. Files maintain their own copy of data and change the data without advising the primary source file. Duplicate data leads to inconsistent data Over time, businesses don’t know which file contains the most accurate data, and can make bad decisions. Data Dependence Physical storage in files Delimiters, parsing and concatenating Files store things in structures or lines of text and they are called flat files. Delimiters are non-text characters separating data elements, and can be XML tags. Position specific files Files organized by physical position define what character range contains a data element. Incompatible File Formats Programming languages differ Programmers solve problems differently Files written by C/C++ differ from files written by COBOL or RPG. Organization of files differs dependent on how the programmer saw the problem. Formats differ Data structures differ between files and require mapping their differences. Fixed Queries Fixed queries report or enter data Fixed queries are written by programmers These are programs dealing with one or more files that are reports or data entry forms. Programmers write reports and forms as requested and budgeted by organizations. Fixed queries don’t answer Ad Hoc questions Impromptu end-user questions can’t be answered without the assistance of an IT organization. Security Limitations File ownership limits File change limits Primary source files are controlled by one organization in businesses. Primary source files are changeable only with permission of the owning organization. File confidentiality Primary source files are viewable as a whole and cannot be restricted by data elements, resulting in compromised confidentiality. File System Limitations Review Section #1 Separating and Joining Data Duplicating Data Data Dependence Incompatible File Formats Fixed Queries Security Limitations Database Systems Section #2 Database Instance Database Management System Standard Language Interface Security Privileges & Roles Database Types Database Instance Data and the definition of data are stored in an organized way. Data is stored in tables that are 2D arrays, like a spreadsheet. Data definition is metadata, or data about data, which is also stored in tables. Data can also contain stored programs that let you access data. Database Management System Programs that manage and access the database instance. Programs that let external programs access the database instance. Programs that control access to the database instance. Programs that backup and recover the database instance. Standard Language Interface Structured Query Language (SQL) Structured English QUEry Language (SEQUEL) ANSI Standards ANSI ANSI ANSI ANSI ANSI SQL-86 SQL-89 SQL-92 SQL:1999 SQL:2003 Security Privileges & Roles Security is tiered by ANSI-SPARC rules Superuser grants privileges to users Superuser – holds internal data Administrator – holds conceptual data User – holds external data Grants individual privileges one at a time. Creates roles as groups of privileges. Grants grouped privileges as roles. Data can be restricted at various levels Database Types Database types Operational – dynamic, time-independent, and critical business operational data. Analytical – statistical, historic, and time-dependent business data. Database implementation types Online Transactional Processing (OLTP) – business applications, also known as operational databases. Online Analytical Processing (OLAP) – data warehouses, also known as analytical databases. Database Systems Revised Section #2 Database Instance Database Management System Standard Language Interface Security Privileges & Roles Database Types History of Databases Section #3 File Systems Hierarchical File Systems Networked File Systems Relational Databases Object Relational Databases Also known as Extended Relational Databases Object-Oriented Databases File Systems Files were the first way to organize data. Files contain related data in structures. File systems contain files, and they duplicate and corrupt copies of data. File systems are programming language specific, restricting file sharing. File systems have too many structures. Hierarchical File Systems Are defined by an inverted tree The top most node is a parent, who can have child nodes, and the bottom node is a leaf node – by a parent-child pointer. You navigate from the top most node to all subordinate nodes, which becomes expensive when data is spread out. Networked File Systems Are also defined by an inverted tree The top most node (also a set structure) links by a pointer or list of pointers to other set structures or nodes. Searches are made from node to node through pointers that associate a node with subordinate nodes or set structure. Relational Databases Are defined by tables. Tables are defined by a list of columns, known as a signature. Metadata tables hold definitions of tables. Links between tables are dynamic relationships as opposed to stored pointer structures. Relationships between tables are made by comparing values in columns, and columns are known as primary and foreign keys. Object Relational Databases (Extended Relational Databases) Are defined by objects, which can be tables, nested collections, or objects with methods. Objects are defined by a list of columns, known as a signature, which can contain methods. Metadata tables hold definitions of objects. Links between objects are dynamic relationships. Relationships between objects are made by comparing values in columns, and columns are known as primary and foreign keys. Object-Oriented Databases Are defined by instantiable objects with methods. Objects are defined by a list of attributes with a constructor and methods. Metadata tables hold definitions of objects. Links between objects are dynamic relationships. Relationships between objects are made during instantiation of object instances by dynamic marshalling. History of Databases Review Section #3 File Systems Hierarchical File Systems Networked File Systems Relational Databases Object Relational Databases Also known as Extended Relational Databases Object-Oriented Databases Pros & Cons of Databases Section #4 Advantages Data redundancy control, consistency, sharing, integrity, security, access, responsiveness, concurrency, independence, and backup/recovery. Disadvantages Complexity, conversion costs, performance, and all-or-nothing risk of catastrophic failure. Database Careers Section #5 Database Administrator (DBA) Physical Database Administrator Application Database Administrator Database Analyst Database Designer Database Programmer Database Administrator (DBA) Physical Database Administrator Physical file administration and ownership Startup and shutdown authority Backup and recovery responsibility Application Database Administrator Privilege and role administration User/schema administration Operations and tuning administration Database Analyst Database physical model implementation Translation of logical design to physical model Analysis of query performance Analysis of index performance Database data integrity Analysis of insertion, update and deletion anomalies Analysis of primary and foreign key validation Database Designer Define a data model for business process Meet with users and define requirements Understand the purpose of the business Design a logical model to manage data Define primary and foreign key relationships Render model and generate build scripts Secure business acceptance of model Database Programmer Define a business processes Meet with users and define requirements Understand the purpose of the business Design a program architecture for process Write programs to support process Coordinate unit and integration testing Document and release code to production Database Careers Review Section #5 Database Administrator (DBA) Physical Database Administrator Application Database Administrator Database Analyst Database Designer Database Programmer Summary File System Limitations Database Systems History of Databases Pros & Cons of Databases Database Careers