chapter 4 - part 1

chapter 4 - part 1 - COP 4710: Database Systems Fall 2007...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
COP 4710: Database Systems (Chapter 4) Page 1 © Mark Llewellyn COP 4710: Database Systems Fall 2007 Chapter 4 – Relational Query Languages – Part 1 School of Electrical Engineering and Computer Science University of Central Florida Instructor : Dr. Mark Llewellyn markl@cs.ucf.edu HEC 236, 823-2790 http://www.cs.ucf.edu/courses/cop4710/fall2007
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
COP 4710: Database Systems (Chapter 4) Page 2 © Mark Llewellyn Mapping E-R Diagrams to Relational Schemas PRACTICE problem from previous notes customer amount merchant-id cust-name date bank-num card account address address exp-date debit card merchant d card-type = ‘D’ ‘C’ current-bal card-type credit card has customer-id has charges account-id
Background image of page 2
COP 4710: Database Systems (Chapter 4) Page 3 © Mark Llewellyn Mapping E-R Diagrams to Relational Schemas SOLUTION to practice problem customer-id customer customer-name customer-address account-id card account expr-date acct-type customer-id d-acct-id debit card bank-num c-acct-id current-balance credit card c-acct-id charges merchant-id date amount merchant-id merchants merchant-address
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
COP 4710: Database Systems (Chapter 4) Page 4 © Mark Llewellyn A query language is a language in which a database user requests information from the database. Most query languages are on a higher-level than standard programming languages like C and Java. Query languages fall into a category of languages known as 4GL. Query languages can be broadly categorized into two groups: procedural languages and nonprocedural languages. A procedural query language requires the user to specify a sequence of operations on the db to compute the desired result. (User specifies how and what.) A nonprocedural query language requires the user to describe the desired result without needing to specify the sequence of operations required to obtain the result. (User specifies only what.) Query Languages
Background image of page 4
COP 4710: Database Systems (Chapter 4) Page 5 © Mark Llewellyn Most commercially available relational database systems offer a query language which is categorized as a hybrid query language. Hybrid query languages include elements of both the procedural and nonprocedural approaches to query languages. For the time being we are going to examine “pure” relational query languages. These languages are terse and formal and lack many of the syntactic elements available in commercial languages, but they illustrate the fundamental techniques utilized by all query languages for extracting data from the database. Query Languages (cont.)
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
COP 4710: Database Systems (Chapter 4) Page 6 © Mark Llewellyn As we examine these pure languages, bear in mind that, although the pure languages do not contain such features, a complete query language has facilities for inserting and deleting tuples from relations as well as for modifying existing tuples.
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 35

chapter 4 - part 1 - COP 4710: Database Systems Fall 2007...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online