K204 Chapter 6

field in a database table

used to store values representing a certain attribute of an entity

database field

• container that will accept only a specified type of data

  • number, text string, a date, Yes/No, 1or0, T/F

1st step to ensuring accuracy, consistency, data integrity?

specifying appropiate data type

Field Properties

specify parameters like max. # of characters allowed, format used, range of values accepted, whether data entry is required for a field

• Boolean (Yes/No) data type field don’t have field size property b/c values are predetermined

Field Properties (6)

1. Field Size

   1. auto. set to Long Integer

2. New Values

   1. normally set to Increment, but can be random. gen.

3. Format

   1. determines how values are displayed

4. Caption

   1. used to create an alt. label to be displayed instead of field name

5. Indexed

   1. sorting + searching more efficient

   2. PK always set to Indexed (No dupes)

6. Text Align

   1. in Access, contents of field can display on L, R, or center

Lookup Fields

• typically a menu of items users select from

• ensures consistency (spelling, entry)

Lookup Field Properties

• Display Control

  • designates type of (user interface) control used

    • Combo Box = used to display “dropdown box”

• Row Source Type

  • determines source of lookup values

Format Property

• has no effect on values stored

• PURPOSE: alter how values are displayed

Caption Property

• to display a descriptive, more user-friendly label in place of field name

  • displayed instead of field name in DATASHEET VIEW

  • field name remains tho

Validation Rule Property

• used to specify a given range of values that can be stored in a field

  • an expression that completes the phrase

  • when specifying numeric ranges, need to use operators

Validation Rule Property - when specifying numeric ranges, need to use operators

Validation Text Property

• display a message to user if invalid data is entered into the field

Required fields act as _________ _______ for well-structured + reliable database

building blocks

Required fields guarantee the following:

1. Data Integrity

2. Enforce Relationships

3. Data Analysis + Reporting

4. Data Entry Efficiency

Data Integrity

critical info always present, prevent incomplete data

Enforce Relationships

RF can be used to link tables together

• enforces data consistency + makes it easer to retrieve related info. across tables

Data Analysis + Reporting

if specific fields always present, can be confident when querying for reports + analysis

Data Entry Efficiency

RF can streamline process, prevent users from accidentally leaving out crucial ddetails

__________, _________ + __________ Name Must be Provided

MemberSince, First, Last

Short Text appears in 3 states

1. newly created record and value inside is NULL (empty) - not visible but there

2. field contains a text string like “Jane” - no longer NULL

3. existing text string is deleted - new value called “Zero Length” string or “Empty string”

   1. set allow zero length property to NO - makes sure fields are never left blank