A. Data base is comprised of 3 levels
1. File
2. Records
3. Flds
B. Two types of data bases are Flat (invoice) and relational(baseball)
C. Relational DB
1. Started by E. F. Codd (the 60's)
2. In a relational DB, data is stored in multiple tables. The
tables are then linked or JOINED.
3. Advantages of relational DB
a. faster
b. focused-easy to understand
c.No redundant data
4. Key field and match fld
a. Key field contains
a unique value to identify a record
b. a Match fld is a common fld between two related files.
5. Lookup vs. relationship
a. Lookup copies data
from one file into another.
b. related data from one database is DISPLAYED in another database
but does not become part of that database
6..Types of relationships
a. one to one (rare)
b. one to many (used often)
c. many to many (can't be done directly in a relational database)