File and Database Design Class 22

File and database design: 1. Choosing the storage format for each attribute from the logical data model. 2. Grouping attributes from the logical data model into physical records. 3. Arranging related records in secondary memory so that individual and groups of records can be sorted, retrieved, and updated rapidly. 4. Selecting media and structures for storing data to make access more efficient.

What we’re looking at Fields, Records, Files, Databases

Fields Name Data type Primary key(s) Data Integrity Handling missing data Ownership

Data Integrity Default Value Picture Control Range Controls Referential Integrity Null Value Control

Records A group of fields stored in adjacent memory locations and retrieved together as a unit. Denormalization (which you’ll learn in the Database class) will be done on records.

Files Different types of files: – Master File – Look-up Table file – Transaction file – Audit Trail – History files

2 File Organization Types Sequential Indexed

What to consider in choosing file organization Fast data retrieval Efficient use of storage space Protection from failures or data loss Accommodating growth Security from unauthorized use

Designing a relational database Create a table (file) for each entity type. Choose a primary key for each table. Create new tables to represent many-to-many relationships. Add foreign keys to represent one-to-many relationships. Define referential integrity constraints. Evaluate schema quality and make necessary improvements. Choose appropriate data types and value restrictions for each field.