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Appendix N: Data Dictionary

The Data Dictionary does not contain any application data, it contains information which describes how that application data is stored, and optionally how that data is to be processed by the application. This information may include table names and characteristics, field names and characteristics, relationship information, et cetera. It is therefore data-about-data, or meta-data.

To utilise this data dictionary there are four distinct stages:

  1. IMPORT - Populate the dictionary database using details extracted from the physical database schema. This includes all field names and their attributes, and all primary keys, candidate keys and indeces. If any table details are subsequently modified the import function can be used again to synchronise the dictionary. This will deal with new tables and new, changed or deleted columns. Note that the database structure must be maintained using an external process.
  2. EDIT - Modify the details for use by the application, including any relationships between tables.
  3. EXPORT - Make the details available to the PHP application in the form of disk files which can be incorporated into scripts by means of the include() function. Note that it is not possible to change table structures within the dictionary then use the export facility to apply these changes to the application database.
  4. GENERATE TASKS - Select a table, then select a transaction pattern and have the system automatically generate all the relevant scripts.

Note that the Export to SQL function works at the database level while the Export to PHP function works at the table level. The files produced are in different formats because they have different purposes.

The design of this Data Dictionary application is explained in A Data Dictionary for PHP Applications.

These are the maintenance screens for the Data Dictionary application which has been built into this infrastructure:

List Databases
List Databases by Subsystem
Import Database
Delete Database
Enquire Database
Erase Database
Export Database to SQL
Search Database
Update Database
Output Databases to PDF (List View)
List Tables
List Tables by Database
Import Tables
Export Table to PHP
Delete Table
Enquire Table
Search Table
Update Table
Choose Table
Output Tables to PDF (List View)
Generate PHP scripts (a) - Select Pattern
Generate PHP scripts (b) - Enter details
List Columns
List Columns by Table
Import Columns
Delete Column
Enquire Column
Search Column
Update Column
Output Columns to PDF (List View)
Output Columns to PDF (Detail View)
List Keys
List Keys by Table
Delete Key
Enquire Key
Search Key
List Relationships
List Child Relationships by Table
List Child Relationships by Database
Add Child Relationship
Update Child Relationship
Enquire Child Relationship
List Parent Relationships by Table
List Parent Relationships by Database
Add Parent Relationship
Update Parent Relationship
Enquire Parent Relationship
Delete Relationship
Search Relationship
Output Relationships to PDF (List View)
Output Relationships to PDF (Detail View)