Database - Chapter 8 Database and SQL Objective What...

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Chapter 8 Database and SQL
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What database is What is relational database What are the types of relationships How to create relationships among entities How SQL is used to retrieve and sort records from a database Objective
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A collection of data about a topic or topics of interest. Objective Data In -- Information Out Database But Remember Garbage In -- Garbage Out! So, be careful as you work with data!
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A D atab ase M anagement S ystem (DBMS) is a software program that is used to manage data in a database: add, change, delete retrieve sort report form archive DBMS
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A relational database is one in which data entities are related to each other. A database file or table or entity columns or fields or attributes Files (tables) are managed by a DBMS Relational Database Student_I D Student_FNa me Student_LNa me Student_Pho ne G002659 8 Fred Smith 703 336 6589 G036598 2 Anne Ebby 703 695 5879 G036986 5 Mike Watson 541 899 4569 Primary Key
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Student Class Professor Major Advisor In a database for a university, the entities might be - Entity
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Class Professor Entities are linked by relationships Relationship is a common item (field) between the tables. The relationship between any two entities can be Quantified: 1:Many Many:1 Many:Many 1 Many One (1) professor teaches many classes. Relationship quantification is called Cardinality. Relationships
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1:M Each manager has many employees Relationship between Manager and Employees
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Class Student Many Many Psych 100 Paint 318 Econ 207 Each student may register in several classes & each class enrolls many students . Relationships between Students and Classes
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Map of the database Schema Student Class Advisor Major Professor Many One Legend: One Many
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Data Redundancy Prof_ID Prof_FName Prof_LName Prof_Phone Course_ID Course_Title G0236958 Amy Gordon 202 236 6598 IT 103 Intro. to Computing G0236958 Amy Gordon 202 236 6598 IT 213 Computer Graphics G0989782 Bill Lyons 703 236 2356 IT 331 Web Development G0236958 Amy Gordon 202 236 6598 IT 223 Computer Security A database file could have records for all students and their courses. Putting all data in one file can be inefficient! Can you spot the data redundancy ?
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wasted disk space slower processing data inconsistency ?
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Database - Chapter 8 Database and SQL Objective What...

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