ACCESS (CHAPTER 2-3 continued)

Naman Kohlinaman.kohli@mail.wvu.edu

October 16, 2013

1

UPCOMING DEADLINES

• 21st October – MyITLab Lesson C

• 1st November – Homework 4 (published)

• 4th November – MyITLab Lesson D

• 8th November – Homework 5

2

MID SEMESTER GRADES

• Those not doing well. Can be seen on STAR.

• Out of 280 – Exam, Homework # 1,2,3

• Still 720 + 60 Bonus points left.

• Focus on MyITLab and Exam 2.

3

PREVIOUS CLASS

4

TABLE RELATIONAL STRUCTURE

5

Members Bands

Countries

∞

∞

1

1

USING “LOOKUP” TYPE FIELDS

• They allow for clicking a drop down arrow when entering field values while in datasheet view to select predefined items as opposed to having to type them.

• Eg:‘Year’ is a Lookup Type Field

• Two types of lookup fields:1. Lookup references uses field values in another table2. Lookup references items you manually enter in

advance in the same table

We will now do both types…

6

LOOKUP FROM OTHER TABLE EXAMPLE

Create the third table for our database called Countries

Make these fields:

ID AutoNumber (Primary Key)

Country TextFlip to Datasheet view and save the table

…

7

LOOKUP FROM OTHER TABLE EXAMPLE

Create the following Records:

1, England

2, America

Close the table

…

8

LOOKUP FROM OTHER TABLE EXAMPLE

Return to the “Members” table in Design View

Add a 5th field called Origin of type Lookup Wizard

Use “I want the lookup column to look up values in a table or query”

Select “Table: Countries”

…

9

LOOKUP FROM OTHER TABLE EXAMPLE

Add the Country field to Selected fieldsNext… Next… FinishSave if promptedReturn to Datasheet View in “Members”

Click in the Origin file to assign these:Assign “England” to The Who membersAssign “America” to Van Halen members.

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SAME TABLE LOOKUP EXAMPLE(LIKE STEP 5H) In the Members table of our example, return

to Design ViewCreate a filed called Instrument of type

Look-up Wizard…Select I will type the values I want.Enter the following:

Vocals, Drums, Guitar, BassSave, Return to Datasheet view to enter

them!

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SAME TABLE LOOKUP EXAMPLE(LIKE STEP 5H)

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Members

BandNum FirstName LastName Origin Instrument

1 John Entwhistle England Bass

1 Pete Townsend England Guitar

1 Roger Daltry England Vocals

1 Kieth Moon England Drums

2 David Lee Roth America Vocals

2 Edward Van Halen America Guitar

2 Alex Van Halen America Drums

2 Michael Anthony America Bass

“YES/NO” FIELD TYPE EXAMPLE

Add a field called “Living”Make it of Type Yes/NoSave the table and mark all records except

Keith Moon and John Entwhistle as Living members

* We will come back to this

13

DATE FIELD EXAMPLE

• Add a field called Born of Date/Time datatype

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Members

Born

10/9/1944

8/23/1946

3/1/1944

5/19/1945

10/10/1954

1/26/1955

5/8/1953

6/20/1954

CREATE A RELATIONSHIP EXAMPLE

Close the tablesOpen RelationshipsNote that lookup wizard created one already!Right click, Show Table, add Bands.Drag [Bands/BandNum] to

[Members/BandNum]Enforce referential, Create, and save.…

15

QUERY EXAMPLE

• We want to use the relationships we created between the tables to show the names of the artists, their band names, and their countries of origin despite only having a band number in the Member table and a lookup for country.

• We can use the relationship to seamlessly query between fields in the three tables and give the desired results…

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QUERY EXAMPLECreate query in design view

Create Ribbon > Query Design buttonAdd all tables (note the relationships showing)From Bands table double click to add: BandNameFrom Members table add: FirstName, LastName, Instrument, LivingFrom Countries table add: CountryRun the Query !Close and Save Query as RockTrivia

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CREATING “AND” CONDITIONIN THE DESIGN GRID…

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LET’S TRY AN “AND”

Clear any existing criteriaType England in the Country row and

create the AND condition by placing Yes in the Living row to return all living band members from England

Run itGo back and change Yes to No and

rerun…

20

LET’S DO AN “OR”

Remove the old criteria

We will set the criteria to show all members from The Who OR anyone from any band that is living at all from the list of members…

First lets put “The Who” in the [Bands] Name field and run to see the results

…

21

CREATE THE “OR”

• We wish to not only see the members of The Who, but also in addition to them, anyone that might be alive in the members table.

In Design view, type “Yes” in the OR row for [Members] Living

You should now see a list of 4 additional records (8 total)

22

SORT EXERCISE

Open the RockTrivia Query in Design ViewIn the Sort row for the BandName field,

have it sort the records in Ascending OrderRun the Query

…

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TWO-LEVEL SORT

Leave the existing sort in place and move the last name field so that it is before the first name field in the Design view…

Click once to select it… let go and then click and drag to move it over

Add a secondary sort by having it do Last Name in Ascending order

Run it. Last names are now show alphabetically inside the band names

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WE CAN ALSO USE “WILDCARDS”

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WILDCARD EXAMPLE

We want to see all members whose last names begin with “E”…

Remove all existing sort optionsIn the last name field, type the letter E in

Criteria and run the query.(No results show as no one has just the letter E for a last name)

Make it read E* and rerun to get any other characters…

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WILDCARDS CONTINUED

Change the criteria to show people whose last names end in “N”*N

Run it and we should see 3 records.Remove all criteria.

USING FIELDS WITHOUT SHOWING

• It is possible to use a field in searching but not show that field in the query results

• Let’s say we want to see all band members whose bands begin and end in “d”, but not see the band name

Remove the “Show” row checkmark for BandName

Create the criteria and run !

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CALCULATIONS IN A QUERY…

• Queries can be built to perform a calculation as part of the query

• We often do this for things that we do not need to store and take up space with

• Expressions can be entered into the query design grid as if they were regular fields

• Done on Numeric data type fields

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CALCULATIONS IN A QUERY…

• To perform a calculation in a query, you must add a calculated field to the query design.

• Make certain that you are following the rules of precedence !

• Two options for entering expressions: – Enter the expression directly into the field text

box– Enter the expression in the Expression Builder

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CREATING A CALCULATED FIELD

Remove the existing criteria In design view, click in the next available

field, where the name would be, and then click the magic wand “Builder” icon above.

The expression builder shows up…

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THE EXPRESSION BUILDER…

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LET’S MAKE A QUERY TO TRY THIS…

We want to figure out how many years they have/would been alive. It would be inefficient to store this and we would have to update it all the time too !

Build or type the following:

Age: (Date()-[Members]![Born])/365

Note: If you see <<expr>> be sure to remove it ! ! !Run it !Expand the width of the column if you see ####

…

33

CHANGING DECIMALS PRECISION

In design view, right click Age fieldClick PropertiesSelect Fixed for Format and 0 for Decimal

PlacesRe-run it to see it without the decimal

places