11 3 / 12 CHAPTER Databases MIS105 Lec15 Irfan Ahmed Ilyas

11 02/3/2002Prepared By: Irfan Ilyas2 Lecture Objectives DBMS Main Modules Some example DBMS packages Introducing Microsoft Access Details of DBMS Interface Objects Table Object Functionalities –Data Definition –Data Manipulation Data Type Details –Character/ Number/ DateTime/ YesNo etc.

11 02/3/2002Prepared By: Irfan Ilyas3 DBMS Examples Most widely used DBMS packages are –Microsoft Access from Microsoft Corporation. –Corel Paradox from Corel –Lotus Approach from Lotus(IBM) –DB2 from IBM –Oracle 8 Personal Edition from Oracle Software –SQL Anywhere Professional from Sybase –SQL Server from Microsoft Corporation.

11 02/3/2002Prepared By: Irfan Ilyas4 Introducing Microsoft Access Two main program components –Microsoft Jet Engine Responsible for managing the data in the database file Controls the structure/ physical details of data on the disk –User Interface Objects Provide an easy to use view to the stored data Forwards the user demands to the Jet Engine in form of SQL commands

11 02/3/2002Prepared By: Irfan Ilyas5 Microsoft Jet Engine..Introducing Microsoft Access Access Database File Data Definition Module Data Manipulation/ Retrieval Module Database Creation Module Database Security Module Database Application Database Operators/ Designers/ Programmers Database.mdb Microsoft Access User Interface Table Object Query Object Form Object Report Object Page Object Macros/ VBA Modules SQL Command Interface End User DBA

11 02/3/2002Prepared By: Irfan Ilyas6 Details of DBMS Interface Objects All DBMS packages allow the use of SQL commands for database interactions Most of the commercially available DBMS packages allow database interactions with graphical interface objects like –Table –Query –Form –Report

11 02/3/2002Prepared By: Irfan Ilyas7 …DBMS Interface Objects Table Object –A table object enables the users to #1: define and create a data file structure inside the database #2: populate/ delete/ modify data records in a particular data file #3: Analyzing data records using tools like pivot table and pivot chart Example: Table object in Microsoft Access

11 02/3/2002Prepared By: Irfan Ilyas8 #1.Table object for Data Definition Table object provides data definition through a design screen (Microsoft Access: Table Design View) Data Definition results in Record Structure Definition for a particular data file (table) The definition includes Name of each field Data type for each field Primary key specification Size of the field (in bytes) Field displaying format Field Input Mask Field entry essentiality Field default value Field validation rule Field indexing Access Table Design Screen (A STUDENT table is shown here)

11 02/3/2002Prepared By: Irfan Ilyas9..Data Definition Details Field name –Every field is assigned with a name –Every DBMS has its own Naming Rules in terms of length, valid characters usage etc. Field Data type –It specifies the type of data values which a particular field will be accepting –Most basic types (available in almost all DBMSes) are Character –Text or combinations of text and numbers, as well as numbers that don't require calculations, such as phone numbers –Microsoft Access »Text – max size= 255 characters (unused characters are not allocated) »Memo – max size= 65,536 characters (unused characters are not allocated) –Microsoft SQL Server »char –fixed size = 8KB (unused characters will be allocated) »varchar – variable size, 8Kb max (unused characters are not allocated) »text – sizes > 8Kb

11 02/3/2002Prepared By: Irfan Ilyas10..Basic Data Types in DBMS Number Numeric data used in mathematical calculations. The max/ min value depends upon the field size allocated. Microsoft Access Number/ Byte - Integer (whole number, only positive) data from 0 through 255 (1 byte) Number/ Integer - Integer (whole number) data from 2^15 through 2^15-1 (2 bytes) Number/ Long Integer- Integer (whole number) data from 2^31 through 2^31-1 (4 bytes) Number/ Single –Real (with decimal) data with 7 digit precision (4 bytes) Number/ Double -Real (with decimal) data with 15 digit precision (8 bytes) Microsoft SQL Server bigint - Integer (whole number) data from -2^63 through 2^63-1 int - Integer (whole number) data from -2^31 through 2^ smallint - Integer data from 2^15 through 2^ tinyint -Integer data from 0 through 255. decimal - Fixed precision and scale numeric data from -10^38 +1 through 10^38 –1. float - Floating precision number data from -1.79E through 1.79E real- Floating precision number data from -3.40E + 38 through 3.40E + 38.

11 02/3/2002Prepared By: Irfan Ilyas11 …Basic data types in DBMSes Date/ Time –For saving date & time values. –Microsoft Access Date/ Time - Date and time values for the years 100 through (8 bytes) (Example: 1/1/100 12:00:00 PM) –Microsoft SQL Server datetime - Date and time data from January 1, 1753, through December 31, 9999 smalldatetime -Date and time data from January 1, 1900, through June 6, 2079

11 02/3/2002Prepared By: Irfan Ilyas12 …Basic data types in DBMSes Yes/ No –To save any one of two possible values. –Microsoft Access Yes/No - fields that contain only one of two values (Yes/No, True/False, or On/Off). [1 bit] –Microsoft SQL Server bit - Integer data with either a 1 or 0 value.

11 02/3/2002Prepared By: Irfan Ilyas13 …Basic data types in DBMSes Binary Data –To save huge binary data/ computer files. –Microsoft Access OLE Object (Up to 1 giga-byte or disk space available) –An object (such as a Microsoft Excel spreadsheet, a Microsoft Word document, graphics, sounds, or other binary data) –Can be linked to a computer file or embedded as a separate object –Microsoft SQL Server binary - Fixed-length binary data with a maximum length of 8,000 bytes. varbinary - Variable-length binary data with a maximum length of 8,000 bytes. image - Variable-length binary data with a maximum length of 2^ (2,147,483,647) bytes.

11 02/3/2002Prepared By: Irfan Ilyas14 …Basic data types in DBMSes Hyperlink –To save a link to an object on web (URL) or network (UNC) –Microsoft Access Hyperlink – can save http and UNC addresses Example: – –\\cim-irfan\mis105\quiz-1.doc\\cim-irfan\mis105\quiz-1.doc –Microsoft SQL Server Not available

11 02/3/2002Prepared By: Irfan Ilyas15..Data Definition Details Primary key specification –To specify the key field for a particular table –This declaration results in Field data to be essentially required Field data uniqueness Field indexing (for fast searching) Example (Microsoft Access) –Entering the same IdNumber (PK in the table) more than once. Unacceptable Record

11 02/3/2002Prepared By: Irfan Ilyas16..Data Definition Details Microsoft Access includes (covered in lab practices)

11 02/3/2002Prepared By: Irfan Ilyas17..Data Definition Details …Microsoft Access includes (covered in lab practices)

11 02/3/2002Prepared By: Irfan Ilyas18 #2.Table object for Data Manipulations Table object provides data manipulations through a data entry screen (Microsoft Access: Table Datasheet View) Data manipulation involves the following activities –Adding new records –Deleting existing records –Modifying existing records –Searching/ Replacing record values –Filtering data records

11 02/3/2002Prepared By: Irfan Ilyas19 ….Table object for Data Manipulations Issues related to data manipulation –Indexed fields Depending the number of indexed fields, the data entry could be slower –Abiding Data Integrity Constraints Data values (entered by the user) must conform to certain constraints These constraints are derived from the meaning or semantics of the data and its environment. Implementing these constraints results in increased degree of data validity throughout the database.

11 02/3/2002Prepared By: Irfan Ilyas20 #3: Table object for Data Analysis Table object provides data analysis feature by making use of pivot table/ chart creations (Microsoft Access: Table Pivot Table View) With a pivot table –Users can do different statistical operations like average, max, min etc. on some specific field value –The operations can be categorized on the basis of one or more fields.

11 02/3/2002Prepared By: Irfan Ilyas21 …. Table object for Data Analysis For example, –In a table saving data about student scores –A pivot table showing score averages while classifying the records with student majors –Same table having a data classification on student major and student class basis

11 02/3/2002Prepared By: Irfan Ilyas22