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Microsoft Access Introduction to Relational Databases Powerful tool to collect and analyze business data, facilitates decisionmaking PgP MIS 202 Access Overview 1 Database Concepts-Databases Relational Database-collection of related tables Common Field-connect records in separate tables Primary Key-field(s) uniquely identify record Foreign Key-Primary Key from one table is Common Field in another table PgP MIS 202 Access Overview 1-2 Database Concepts-RDBMS Relational database management system functions Create database structures Add and edit records Query capability (SQL) Report generator Data validation and protection Data sharing Ability to handle large amounts of data PgP MIS 202 Access Overview 1-3 Database Concepts-Tables Field-single characteristic of a person, place, object, event or idea Table-collection of fields that describe a person, place, object, event or idea Field Value-specific field content Record-set of field values PgP MIS 202 Access Overview 1-4 Database Objects-Queries Select queries answer questions using data stored in a database Action queries change database data Query Wizard enables learning query creation PgP MIS 202 Access Overview 1-5 Database Objects-Forms Allows you to maintain and view records in a database Mainly for on-screen output Form Wizard enables learning form creation PgP MIS 202 Access Overview 1-6 Database Objects-Reports Allows you to view records in a database More formatting flexibility and options than a form Mainly for printed output Report Wizard enables learning report creation PgP MIS 202 Access Overview 1-7 Database Administration Compacting-delete unused objects, defragments the database Backup-protect from data loss or damage Restore-to make sure your backup scheme is working Convert databases, link tables Many other topics-journaling, rollback… PgP MIS 202 Access Overview 1-8 Microsoft Access Database and Table Design Requires up front planning to create useful database PgP MIS 202 Access Overview 9 Designing Databases Determine fields needed to produce information to make decisions (forms, reports) Group fields by subject/topic into tables Create primary key for tables Determine and set field properties Include common fields to link tables Normalize to avoid data redundancy PgP MIS 202 Access Overview 1-10 Designing Tables Tables are composed of fields, set field properties to accomplish your goal Develop and use a field naming convention Understand and set field data types Decide on field size, be aware of storage and performance issues PgP MIS 202 Access Overview 1-11 Design Aids Database and Table Wizards Learn typical field settings and properties by observing how Microsoft does it PgP MIS 202 Access Overview 1-12 Table Design View Choose Field Name and Data Type Description appears in status bar, good to add Choose Field Properties Properties vary by Data Type Common-Field Size, Required, Format PgP MIS 202 Access Overview 1-13 Table Design View Choose Primary Key Indexed: Yes(No Duplicates) unique Indexed Fields speeds up searches but requires CPU cycles Entry required, no null values entity integrity PgP MIS 202 Access Overview 1-14 Table Datasheet View Data Entry Be aware of left column symbols, navigation Data entry can also be done in forms File>Save does not save record, that is done when you move to another record PgP MIS 202 Access Overview 1-15 Table Modifications-Design Be aware of ramifications Possible Field actions: Delete Move Add Modify Properties PgP MIS 202 Access Overview 1-16 Table Modifications-Records Possible actions: Copy(are field structures similar?) Open multiple copies of Access? Delete Modify Copy field value from previous record, Ctrl+’ PgP MIS 202 Access Overview 1-17 Table Relationships Defining and using table relationships is the way to combine related data One to many Unique record from one table can have zero, one or many related records in another table PgP MIS 202 Access Overview 1-18 Microsoft Access Query Basics Obtaining Answers to Data Questions PgP MIS 202 Access Overview 19 Querying Databases Filters-datasheet tools to temporarily display set of records Filter by Selection Filter by Form Advanced Filter PgP MIS 202 Access Overview 1-20 Querying Databases Most common type- Select Query Asks a question about the data stored in tables, only certain records meet the criteria and are selected PgP MIS 202 Access Overview 1-21 Querying Databases Query, Design View Query By Example (QBE) is the Access user interface that creates Structure Query Languate (SQL) statements Query, Datasheet View Display returned records, or ‘answers’ Can be different each time query is run, why? PgP MIS 202 Access Overview 1-22 Querying Databases Creating queries is one of the most important skills in any database program Queries are the basis for forms and reports Good form and report design is a result of starting with a good query design PgP MIS 202 Access Overview 1-23 Querying Databases Sorting, Ascending or Descending Up to 10 fields, done from left to right Show check box- determines if field is displayed in datasheet Why needed? Set criteria for a field that you do not want displayed PgP MIS 202 Access Overview 1-24 Querying Databases Specifying Record Selection Criterialearning to return just the records you need Learn to formulate expressions, used in: Query criteria and calculated fields PgP MIS 202 Access Overview 1-25 Querying Databases Operators- key expression building tool Like, In, Between…And… =, <, >, <> Exact matches Multiple criteria And-tends to return fewer records Or-tends to return more records PgP MIS 202 Access Overview 1-26 Querying Databases Calculated Fields-derivable quantities that should not be stored (why?) in underlying table, such as: ExtendedPrice: Quantity * Price Age: DateDiff("yyyy",[DateOfBirth],Date()) Expression Builder-useful tool Zoom Box (Shift+F2) PgP MIS 202 Access Overview 1-27 Querying Databases Aggregate Functions-useful for gathering statistical information, watch “group by” PgP MIS 202 Access Overview 1-28 Querying Databases Group By-use in conjunction with aggregate functions or alone Consolidate records into groups based on chosen fields Useful in finding unique field values PgP MIS 202 Access Overview 1-29