* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Ch 11:Databases - Content - Faculty Personal Homepage
Survey
Document related concepts
Oracle Database wikipedia , lookup
Concurrency control wikipedia , lookup
Relational algebra wikipedia , lookup
Entity–attribute–value model wikipedia , lookup
Microsoft Access wikipedia , lookup
Open Database Connectivity wikipedia , lookup
Ingres (database) wikipedia , lookup
Microsoft SQL Server wikipedia , lookup
Extensible Storage Engine wikipedia , lookup
Microsoft Jet Database Engine wikipedia , lookup
Clusterpoint wikipedia , lookup
Versant Object Database wikipedia , lookup
Transcript
3 / 12 Databases MIS105 Irfan Ahmed Ilyas More topics on Databases • Databases Advantages • Types of Databases • Databases Uses and Issues • Writing Queries in DBMS 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 2 Databases Advantages – Sharing information • One department to another – Security • Password to access – Less data redundancy • Excess storage reduced – Data integrity • Consistent data 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 3 Types of Databases 11 • Individual database – Integrated files used by one person • Shared database – Common operational – Common user • Distributed database • Proprietary database • Web database Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 4 Database Uses and Issues 11 • Strategic uses – Data warehouse – Data mining • Many databases used everyday – Business directories – Business statistical information – Web search databases • Security issues Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 5 Writing Queries in DBMS 1. What are Queries? 2. Available Query Types • • Data Manipulation Queries Data Definition Queries 3. Creating Queries in Access 1. QBE (Query By Example) 2. SQL (Structured Query Language) 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 6 … Competencies 4. Working with SELECT Queries 1. Using Single Table 2. Multiple table 3. Parametric (Runtime Criteria) Query 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 7 What Are Queries? • Queries help the user to select information from tables for a specific purpose • Queries can – – – – – – 11 Ch 11 Show the selected fields Show selected records from one or multiple table Update selected records Delete selected records Make new tables Append records in an existing table © The McGraw-Hill Companies, Inc. 2000 CE 8 Available Query Types • Data Manipulation Queries • SELECT Queries – • UPDATE Queries – • CREATE TABLE Queries – Ch 11 Delete some database records fulfilling some criteria Data Definition Queries • 11 Add more database records to some table DELETE Queries – • Modify database records (fulfilling some criteria) APPEND Queries – • Show database records fulfilling some criteria Create new table\field types inside the database © The McGraw-Hill Companies, Inc. 2000 CE 9 Creating Queries in Access • QBE (Query By Example) Approach – Allows a visual Query creation – Query Grid allows to • select records from the required tables\other queries • select only the desired field of the records • sort the result on the basis of some field values • specify record selection criteria 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 10 An Example Query in a QBE Grid Query showing Saudi Faculty Members 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 11 …Creating Queries in Access • Using SQL (Structured Query Language) Statements – A standard way of creating Queries – Applicable to all existing DBMS (relational) – A set of statements is used to create Queries In Access: View\ SQL View is used to write Queries directly in SQL 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 12 …Creating Queries in Access • Example SQL Statements SELECT Queries SELECT <field name(s)> FROM <table name(s)> WHERE <condition(s)>; – UPDATE Queries UPDATE <table name(s)> SET <field name= value> WHERE <condition(s)>; 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 13 An Example Query in SQL View Query showing Saudi Faculty Members in SQL View 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 14 Working with SELECT Queries • SELECT Queries show database records fulfilling some criteria • Query Criteria are defined on one or more field values Logical Operators for building Query Criteria • Compound criteria expressions can be made (by using AND/ 11 OR) Ch 11 © The McGraw-Hill Companies, Inc. Example Criteria 2000 Expressions CE 15 Working with SELECT Queries Compound Criteria Queries (AND \ OR) 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 16 1. SELECT Queries: Single Table • Query only needs information from a single table • Example – Faculty information is needed for Saudi Faculty 11 A SELECT Query with single table Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 17 Query Result 2. SELECT Queries: Multiple Table • Query needs information from more than one tables • All tables used must be properly related to each other (using PK\ FK links) • Example – Faculty information including their department name is needed 11 Query Result SELECT Query with multiple tables Companies, Inc. Ch 11 © The McGraw-Hill 2000 CE 18 ….SELECT Queries: Multiple Table • Effect of using tables without any relationships Jobs Table Employee Table 11 Query Result: Cross © The McGraw-Hill Companies, Inc. Product of Records CE 19 Ch 11 Table Query having no relationship Multiple 2000 3. SELECT Queries: Parametric • When? – Criteria value is flexible to change during Query runtime • Example – Faculty information who join the university in a given value of Year (given during runtime) 11 Query Result Variable Value Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 20 11 Ch 11 © The McGraw-Hill Companies, Inc. 2000 CE 21