Presentation is loading. Please wait.

Presentation is loading. Please wait.

Access Tables 1. Creating a Table Design View Define each field and its properties Data Sheet View Essentially spreadsheet Enter fields You must go to.

Similar presentations


Presentation on theme: "Access Tables 1. Creating a Table Design View Define each field and its properties Data Sheet View Essentially spreadsheet Enter fields You must go to."— Presentation transcript:

1 Access Tables 1

2 Creating a Table Design View Define each field and its properties Data Sheet View Essentially spreadsheet Enter fields You must go to design view to set field properties the way you want them Templates(2k7 and earlier) Create table using predefined templates Use design view to change field property defaults of template 2

3 Design View Access 2k7 & 2K10 Select Create Tab Select Table Design Enter your data fields For each field select the data type Based upon data type selected you can set additional properties for the field Enter description (good systems documentation tool) 3

4 Design View Access 2007/2010 Define your Primary Key(s) Highlight field(s) that will be Primary key(s) Select Key symbol to set primary key Save your table You can click on save symbol You will be asked to give table a name Click on close symbol You will be asked if you want to save changes You will be asked to give table a name 4

5 Table Design 5

6 6 Define Data Type Define additional Properties for each Field Enter Fields Enter Description for documentation purposes

7 Data Types 7

8 Common Field Properties ( available properties function of data type) Field Size: determines the length of text and number fields Format: customizes the way fields including number, dates, times, and text appear when they are printed or displayed Input Mask: makes user data entry easier by displaying a mask (template) into which the user types data (xxx)-xxx-xxxx 8

9 Field properties include: Caption: the caption specifies an alternative field name that appears in forms and reports as well as the datasheet view of a table or query More user friendly Default Value: the value that is automatically assigned a field when you create a new record 9

10 Field properties include: Validation Rule and Validation Text: Validation Rule property specifies, in a logical expression, the value(s) or range of values that are permitted for the field. Validation Text is an error message displayed whenever a user enters a value not allowed for the field. 10

11 Field properties include: Required: The required property is Yes or No. When set to Yes, the associated field must have a valueit cannot be empty Indexed: Containing either Yes or No, the indexed property indicates whether or not Access maintains a special, separate data area called an index that speeds searches on the field. Indexed fields are faster to search. 11

12 12 In design view, Highlight field you want to be primary key and select Primary key symbol Primary Key

13 13 Key symbol indicates that Field One is Primary key

14 14 Key symbol indicates that Field One and Field Two are Primary keys

15 15 Enter name you want to Give your table here and click on OK Click on Save symbol

16 16 Click on Close symbol and select yes to save changes

17 17 Enter name you want to Give your table here and click on OK

18 18 Saved Table

19 Data sheet View Access 2007/2010 Select Create Tab Select Table Table with a default primary key is created Click on Add New Field and enter Field Label for each Filed you want in table Enter Design View to define data types and properties for each field Change default Primary Key Field if necessary Save your table 19

20 Data sheet View Access Select Table

21 21 Click on Add New Field and enter Field Label

22 22 Click on View Symbol and select Design View to define field properties

23 23 Define data type for each field and any properties

24 Entering Data into table Enter data for each field in a record Data is automatically saved as you go to enter next record You will not be prompted to save when you exit the table Situations where you will be prompted to save when exiting a table Changes made in design view to field properties Changing display characteristics(how you view it on the screen) 24

25 Table (relation) Properties Each row(record) is unique Columns(fields) for any record(row) Single valued(no repeating groups) Values are like data type 25

26 Primary Key Attributes Primary key is a Field/column (or group of fields/columns) that uniquely identifies a given row(record) the SaleID column, for example (on the next slide) Primary key can not be null (entity integrity rule) Guarantees uniqueness of entities and enables proper referencing of primary key values by foreign key values 26

27 Primary Key Example 27 Primary Key SaleIDDateAmountSalespersonID A6/14$4, B6/14$6, A6/15$1, Sale Table

28 Foreign Key Attribute Foreign key is an attribute in one table that must match the primary key in another table or be null(referential integrity rule) A primary key from a different table that has been posted into the table to create a link(relationship)between the two tables the SalespersonID of Sales Rep table is a foreign key in the Sale Table 28

29 Foreign Key example 29 SalespersonIDName Fred Francis SaleIDDateAmountSalespersonID A6/14$4, B6/14$6, A6/15$1, Sale Table Sales Rep Table

30 Creating Relationships Click on the relationship symbol From the pop up box add the tables Establish the relationship between the tables Enforce referential integrity Cascade updates When exiting relationship view, save your changes 30

31 Referential integrity Referential Integrity are a set of rules that prevent addition, deletion or modification of data in a table if the changes would create a problem with a relationship You cant enter a value in foreign key field of a related table unless theres a matching value in the primary key of the primary(parent) table Example- you cant enter an order for a CustomerID that does not exist in the customer table 31

32 Referential integrity Prohibits removal of a parent table row until all the rows in another table(s) referring to the parent table are first removed You cant delete a customer record from the Customer table if there are associated invoices linked back to the Customer tablein the Invoice table. To remove a Parent table record, you first have to delete all occurrences of child table records. Referential integrity essentially prevents orphansrecords in related tables that have no master record in a parent table 32

33 Referential integrity You cant change primary key value in the primary(parent ) table if there are matching records in the related table(s) If you select cascade update related fields option when establishing referential integrity, changes to primary key in parent table will be updated in the related table(s) 33

34 34 Creating Relationships(2k7 & 2K10) Select database Tools tab and then select relationships

35 35 you will see a box similar to one on right. Select each table and click on add.

36 36 First, Click on SalespersonID Then, drag to matching attribute in other table

37 37 Enforce referential integrity Cascade update s Select create

38 38

39 Primary key/Foreign Key Establishing relationship Primary key/Foreign key must be like type data types Auto# cannot be FK 39

40 Edit Relationship Enter relationship window Right click on the relationship line between tables Select from the pop-up box Edit relationship or delete 40

41 41 Right click on relationship line

42 Database demos & exhibits On class web site 0databasedemos.htmhttp://bergg.etsu.edu/classpages/4310/431 0databasedemos.htm 42


Download ppt "Access Tables 1. Creating a Table Design View Define each field and its properties Data Sheet View Essentially spreadsheet Enter fields You must go to."

Similar presentations


Ads by Google