ch5

Field: A container in a table that stores values for one attribute of an entity (e.g., name, date, rate).

Field Properties: Settings that control what values a field accepts, how they display, and whether they are required.

Why Field Properties Matter: They improve data accuracy, consistency, integrity, and ease of data entry.

Metadata: Information about the database structure (fields, data types, properties, relationships), not the actual data.

Field Size: Limits the maximum number of characters (Short Text) or memory used (Number).

Format Property: Controls how data is displayed, not how it is stored.

">" Format Symbol: Forces text to display in UPPERCASE.

"<" Format Symbol: Forces text to display in lowercase.

Caption Property: Displays a user-friendly label instead of the field name without breaking queries or relationships.

Default Value: Automatically fills a field when a new record is created.

Date() Function: Returns the current date.

Date() − 1: Returns yesterday’s date (used for default values).

Required Property: Forces users to enter a value before saving a record.

Dates Are Numbers: Dates are stored as serial numbers representing days since 12/31/1899.

Why Dates Can Be Calculated: Because dates are numeric, you can subtract them to calculate time spans.

Validation Rule: An expression that defines what values are allowed in a field or record.

Validation Text: Custom message shown when a validation rule is violated.

Logical Operators: AND, OR, NOT — used to combine conditions.

Comparison Operators:

Numeric Range Validation: Limits numbers to a range (e.g., Between 0 And 3000).

Record Validation Rule: Rules that evaluate multiple fields together before saving a record.

NULL Value: A field that has never been filled in.

Zero-Length String (""): An empty value that is not NULL.

Lookup Field: A dropdown list that restricts user input to valid choices.

Value List Lookup: Lookup values typed manually.

Lookup from Table or Query: Lookup values pulled dynamically from another table.

Combo Box: The control used to display lookup dropdown menus.

Row Source: Defines where lookup values come from.

Limit to List: Prevents users from entering values not in the lookup list.

Enable Data Integrity: Automatically enforces referential integrity between tables.

Multi-Field Lookup: Displays multiple columns but stores one value.

Cascade Update Related Fields: Automatically updates foreign keys when a primary key changes.

Field Validation vs Record Validation: Field validation applies to one field; record validation applies to multiple fields.