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:

Databases

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)

Tables

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

Columns

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)

Keys

List Keys

List Keys by Table

Delete Key

Enquire Key

Search Key

Relationships

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)