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COIT 13143 Database Programming and Administration Lecture 1 Welcome to Database Programming and Administration Course Aim is to provide students with introduction to contemporary database development and server technologies being used to support Internet Database Application. Text Book : Kroenke, David M. (2002) Database Processing – Fundamentals, Design and Implementation (8th Edition) Prentice Hall International, Inc. Prepared by: Mohasin Ali Unia and Michael Gregory About Course More emphasis is placed on Assignments Less theoretical contents Open book Exam Goal is to provide platform for undertaking database projects. Course Contents There are 4 modules: More SQL Development Technologies Database Server Technologies Internet Database Application Technologies Prepared by: Mohasin Ali Unia and Michael Gregory Subject Evaluation Criteria Assignment 1 (End of 7th Week) Assignment 2 (End of 10th Week) Final Exam (Open book) - 40% - 20% - 40% ------100% ------- Assignment Questions are available in the Course Profile Prepared by: Mohasin Ali Unia and Michael Gregory Assignment 1 Covers: – Professional Form Development using Access (In preparing for Assignment 1 we will cover Module 2 and an introduction to Access) Notes on Assignment 1 Assignment 1 is due in Week –7 (Friday) Assignment 1 is big. You will be able to make start this week. For Assignment 1, you will be asked to submit a log of all of your work on the Assignment (Read Course Profile) For each session of your work on Assignment 1 , record – – – – – – What you achieved Problems encountered Date and number of hours worked Keep it brief A log between 2 or 4 A4 pages is expected. Study Schedule In the first few weeks we will introduce Application Development in Access. Module 1 covers mostly SQL Module 2 covers Database Development Technologies like Embedded SQL, 4GLs and RAD’s. We will also cover Database Application Architecture – Centralized, Client/Server, FileServer and Distributed. Module 3 and 4 will be covered later in the term What is SQL Structured Query Language (SQL), is the most important relational data manipulation language in use today. It is been endorsed by the American National Standard Institute (ANSI) as the language of choice for manipulating relational databases, and it is the data access language used by many commercial DBMS products, including Oracle, Sybase, SQL Server, dBase, Microsoft Access etc. SQL commands can be used interactively as a query language or they can be embedded in application programs. SQL is not a programming language, it is a data sublanguage or data access language. Database Tables Databases contain objects called Tables. Records of data are stored in these tables. Tables are identified by names (like "Persons", "Orders", "Suppliers"). Tables contain Columns and Rows with data. Rows contain records (like one record for each person). Columns contain data (like First Name, Last Name, Address, and City). LastName FirstName Address City Hansen Ola Timoteivn 10 Sandnes Svendson Tove Borgvn 23 Sandnes Pettersen Kari Storgt 20 Stavanger LastName, FirstName, Address, and City are table Columns. The Rows contain 3 records about 3 persons. SQL Queries With SQL, we can Query a database and have a Result returned in a tabular form. A Query like this: SELECT LastName FROM Persons give a Result like this: LastName Hansen Svendson Pettersen SQL Data Manipulation As the name suggests, SQL is a syntax for executing queries. But the SQL language also includes a syntax to update records, insert new records and delete existing records. These query and update commands together form the Data Manipulation Language (DML) part of SQL: – – – – SELECT - extracts data from a database UPDATE - updates data in a database DELETE - deletes data from a database INSERT - inserts new data into a database SQL Data Definition The Data Definition Language (DDL) part of SQL permits database tables to be created or deleted. We can also define indexes (keys), specify links between tables, and impose constraints between database tables. The most important DDL statements in SQL are: – – – – – CREATE TABLE - creates a new database table ALTER TABLE - alters (changes) a database table DROP TABLE - deletes a database table CREATE INDEX - creates an index (search key) DROP INDEX - deletes an index Result Table The result from a SQL query is stored in a result set. The result set can be thought of as a result table. Most database software allow navigation of the result set with programming functions like: Move-ToFirst-Record, Get-Record-Content, MoveTo-Next-Record...... Where Clause The WHERE clause is used to specify a selection criterion. SELECT column FROM table WHERE column condition value With the WHERE clause, these conditions can be used: Operator Condition = Equal <> Not equal > Greater than < Less than >= Greater than or equal <= Less than or equal BETWEEN Between an inclusive range LIKE Explained next page This SQL statement will return persons with a first name that start with an 'O'. SELECT * FROM Persons WHERE FirstName LIKE 'O%' This SQL statement will return persons with a first name that end with an 'a'. SELECT * FROM Persons WHERE FirstName LIKE '%a' This SQL statement will return persons with a first name that contains the pattern 'la'. SELECT * FROM Persons WHERE FirstName LIKE '%la%' All the examples above will return the following result: LastName FirstName Address City Year Hansen Ola Timoteivn 10 Sandnes 1951 BETWEEN ... AND The BETWEEN ... AND operator selects an inclusive range of data between two values. These values can be numbers, text, or dates. SELECT column_name FROM table_name WHERE column_name BETWEEN value1 AND value2 Example 1 To display the persons alphabetically between (and including) "Hansen" and "Pettersen", use the following SQL: SELECT * FROM Persons WHERE LastName BETWEEN 'Hansen' AND 'Pettersen' Example 2 To display the persons outside the range used in the previous example, use the NOT operator: SELECT * FROM Persons WHERE LastName NOT BETWEEN 'Hansen' AND 'Pettersen' Group By and Having The GROUP BY keywords have been added to SQL because aggregate functions (like SUM) return the aggregate of all column values every time they are called. Without the GROUP BY functionality, finding the sum for each individual group of column values was not possible. SELECT column,SUM(column) FROM table GROUP BY column The HAVING keyword has been added to SQL because a WHERE keyword cannot be used against aggregate functions (like SUM). Without the HAVING keyword it would not be possible to test for function result conditions. The syntax for the HAVING function is: SELECT column,SUM(column) FROM table GROUP BY column HAVING SUM(column) condition value GROUP BY Example This "Sales" Table: Company W3Schools IBM W3Schools SELECT Company, SUM(Amount) FROM Sales And This SQL: Returns this result: Company W3Schools IBM W3Schools Amount 5500 4500 7100 SUM(Amount) 17100 17100 17100 The above code is invalid because the column returned is not part of an aggregate. A GROUP BY clause will correct, as in this SQL: SELECT Company,SUM(Amount) FROM Sales GROUP BY Company Returns this result: Company W3Schools IBM SUM(Amount) 12600 4500 Having Example This SQL: SELECT Company,SUM(Amount) FROM Sales GROUP BY Company HAVING SUM(Amount)>10000 Will give the result: Company SUM(Amount) W3Schools 12600 SQL Join Sometimes we have to select data from two tables to make our result complete. We have to perform a join. Tables in a database can be related to each other with keys. – A primary key is a column with a unique value for each row. The purpose is to bind data together, across tables, without repeating all of the data in every table. In the "Employees" table next, the "ID" column is the primary key, meaning that no two rows can have the same ID. The ID distinguishes two persons even if they have the same name. When you look at the example tables next, notice that: The "ID" column is the primary key of the "Employees" table The "ID" column in the "Orders" table is used to refer to the persons in the "Employees" table without using their names Employee Table : ID Name 01 Hansen, Ola 02 Svendson, Tove 03 Svendson, Stephen 04 Pettersen, Kari Order Table : ID Product 01 Printer 03 Table 03 Chair Referring to Two Tables We can select data from two tables by referring to two tables, like this: Example Who has ordered a product, and what did they order? SELECT Employees.Name, Orders.Product FROM Employees, Orders WHERE Employees.ID = Orders.ID Name Product Hansen, Ola Printer Svendson, Stephen Table Svendson, Stephen Chair Using Joins OR we can select data from two tables with the JOIN keyword, like this (this is the preferred way to do it): Example INNER JOIN Syntax SELECT field1, field2, field3 FROM first_table INNER JOIN second_table Who has ordered a product, and what did they order? ON first_table.keyfield = second_table.foreign_keyfield SELECT Employees.Name, Orders.Product FROM Employees INNER JOIN Orders ON Employees.ID = Orders.ID LEFT JOIN Syntax SELECT field1, field2, field3 FROM first_table LEFT JOIN second_table ON first_table.keyfield = second_table.foreign_keyfield The LEFT JOIN returns all the rows from the first table, even if there are no matches in the second table. If there are rows in First Table that do not have matches in Second Table, those rows also will be listed Right Join Syntax: SELECT field1, field2, field3 FROM first_table RIGHT JOIN second_table ON first_table.keyfield = second_table.foreign_keyfield The RIGHT JOIN returns all the rows from the second table, even if there are no matches in the first table. If there had been any rows in the Second Table that did not have matches in First Table , those rows also would have been listed. Week Activities Subscribe to Majordomo – To subscribe to the mailing list for this course, send an email message to [email protected] – and in the body of the message put subscribe coit13143-t3 end – To post to the list, send your message to [email protected] Complete exercises given in the Study guide. Start working on Assignment 1 – Assignment 1 is big, worth 40% of the Assessment – Aim at: » read and understand assignment 1 » download and explore the database file for assignment 1 » Set up your journal