IE 423 – Design of Decision Support Systems Introduction to Data Base Management Systems and MS Access

MS Access Access is a DataBase Management System (DBMS) It is conceptually similar to other DBMSs  Like MySQL, Postgress, Oracle, DB2 At times Access will look like Excel… …but it is not the same… …in many important ways It meets very different application needs 2

Consider this- Imagine that you live in a dorm.. You want to keep track of who has what music So, if you wanted to borrow one or more pieces of music you would know where to go You create a stack of note cards where each card contains Id and location information people on your floor You create another (bigger) stack of note cards where each one contains info on a specific song and who owns it How would you find out who has “Angel” by Sarah McLachlan and how would you find out how to contact that person? How would you find all Raggae music on your floor? 3 Name: Bob Room: 214 Phone: IM: BadBob Name: Sara Room: 210 Phone: IM: Tallsara Name: Alan Room: 219 Phone: IM: insomniac Name: Mary Room: 236 Phone: IM: ProudMary Name: Bill Room: 255 Phone: IM: Billygoat Song: Margaritaville Artist: Jimmy Buffet Genre: Pop Owner: Bill

Consider this- What are some characteristics of our two datasets? 4 Name: Bob Room: 214 Phone: IM: BadBob Name: Sara Room: 210 Phone: IM: Tallsara Name: Alan Room: 219 Phone: IM: insomniac Name: Mary Room: 236 Phone: IM: ProudMary Name: Bill Room: 255 Phone: IM: Billygoat Song: Margaritaville Artist: Jimmy Buffet Genre: Pop Owner: Bill

DBMS So, some problems for data-based decision support are database problems …and are best addressed by a data base management system (DBMS) So, what do we mean by “database”

DBMS A Data Base Management System (DBMS) is a system for keeping, organizing and enabling the retrieval of information An OS file system is a DBMS (by this definition)

A DBMS has tools to support the use of data in tables

DBMS A DBMS is a software system for developing, organizing, managing and using databases A database is an organized collection of information The data in a database is related in someway The data in a database is structured The term “organized” is loosely defined The term “structured” is loosely defined 8

MS Access Remember our notecards – Each notecard represents an entity – in this case a person or a piece of music In database parlance this is called a “record” A record contains one or more discrete pieces of information on a specific entity These discrete pieces of information (even if they are blank) are called “fields” A group of fields organized together about one entity makes up a record A table has a field that makes each record unique – primary key 9

MS Access - Concepts Database concepts A collection of records organized together and having the same set of fields is a “table” Depending on how you view it (there are several ways) a table looks a lot like a worksheet in Excel  It has rows (records) that represent entities  It has columns (fields) that represent pieces of information about those entities A group of tables on a related topic and stored in one file is a database 10

MS Access - Concepts A database has other objects as well Queries – tools to search for data Forms – a designed screen for entering, managing or correcting data in a database Reports – a tools for organizing and presenting database contents or results in a useful or intelligible form Macros – stored shortcuts of steps that you use in Access Modules – stored programs for automating functionality in Access 11

RDBMS Relational Data Base Management System or RDBMS – A system for keeping, organizing and enabling the retrieval of data, where… data is stored in tables made up of  rows (records),… and  columns (fields)

DBMS vs Spreadsheet Programs DBMS Large amounts of data Relatively static data Focus on retrieval, organization and presentation of data Good multi-user support Good support for complex relations among datasets Spreadsheet Limited amount of data Dynamic data Focus on modifying data Little or no multi- user support Limited support for complex relations among datasets

Some common DBMSs MySQL Postgres Oracle DB2 MS SQL Server MS Access

Some common DBMSs The various DBMS package may look different,… …they have different tools and interfaces,… …have different capacities and performance levels,… …and run on different platforms, but… Under the hood they are the same, at least in principle

MS Access A RDBMS produced by Microsoft Runs on MS Window Meant for non-enterprise level applications, but…

MS Access FeatureLimit Database size2 Gigabytes Objects in db32,768 No. of concurrent users255 Fields in table (record)255 Open tables (concurrent)2048 (approx) Memo field max size65,535 Relationships in query32 per table Tables in a query32

MS Access Major Features Database  Tables  Queries  Forms  Reports  Macros  Modules

MS Access Tables one or more tables per DB (254) can be related Queries views of data from tables single or multiple tables Forms on screen displays for data from tables or queries single records, multiple records from single or multiple tables

MS Access Reports for printed output complex presentations of data single or multiple tables Data Access Pages web access to DB Macros and VB modules programmed responses in DB

MS Access Extensive design features Fairly complex Security control

MS Access Scalability to Enterprise level system Access is fairly substantial Access Projects – Access as a front-end to SQL Server DB links to other systems

MS Access – Memory vs Storage Excel, Word and lot of other applications do there work in memory Your spreadsheet or Word document is held in memory while you work Your changes, edits or new information is not committed to your spreadsheet or document until you do a save Not so in Access While you working on an Access database that database in on a storage device – disk, USB drive, etc. Any changes you make to a record or a table are immediately committed to the database file 23

MS Access – Memory vs Storage One exception – if you currently editing a record those changes only exist in memory, not in the database. You know this by the little pencil icon on the left side of the row that you are editing While you are in this state you can Undo When you move to another row you commit the changes in the previously edited row And you can no longer undo them Remember the changes you make are being posted to the database file as you work…. Not just when you save or exit 24

MS Access – Memory vs Storage Access files/databases can be shared Multiple people can be using them at the same time Make your only copy of any database that you using for this class Change the database file name to have your name as a prefix Store it on a device where you can use it, edit it… 25