access chapter 3-obtaining answers to your data questions
TRANSCRIPT
Access
Chapter 3-Obtaining Answers to Your Data Questions
PgP MIS 342 Access 3-2
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 342 Access 3-3
Table Relationships
Referential Integrity System of rules to ensure that relationships between
records in related tables are valid Prevents accidental deletion of or change to related data Use cascade updates and or cascade deletes to allow
automatic changes to related fields (is it good to use cascading? Depends on the situation)
PgP MIS 342 Access 3-4
Querying Databases
Filters-datasheet tools to temporarily display set of records Filter by Selection Filter by Form Advanced Filter
PgP MIS 342 Access 3-5
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 342 Access 3-6
Querying Databases
Query, Design View Query By Example (QBE) is the Access user
interface that creates SQL statements
Query, Datasheet View The display of the returned records Can be different each time the query is run
PgP MIS 342 Access 3-7
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 342 Access 3-8
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 342 Access 3-9
Querying Databases
Specifying Record Selection Criteria-learning to return just the records you need
PgP MIS 342 Access 3-10
Querying Databases
Learn to formulate expressions, used in: Query criteria and calculated fields
And also: Table validation rules Form and report calculated controls VBA code SQL statements
PgP MIS 342 Access 3-11
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 342 Access 3-12
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 342 Access 3-13
Querying Databases
Aggregate Functions-useful for gathering statistical information, watch “group by”
PgP MIS 342 Access 3-14
Querying Databases
Group By-use in conjunction with aggregate functions or alone Consolidate records into groups based on chosen
fields