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How to document a database
- 1. How to document a database Piotr Kononow Dataedo https://dataedo.com
- 2. Agenda I. Why document II. What is database documentation III. How to document
- 4. Need to data access & analysis is growing Google search https://dataedo.com
- 5. Databases are vague Sample table and column names from real databases: • MTL_SYSTEM_ITEMS_B – Raw materials? • tP – Projects. Who would guess… • BEN_PRTT_RMT_RQST_CTFN_PRVDD - ? • RSRCSECX - ? • ATTRIBUTE5 – Who knows… https://dataedo.com
- 6. Databases are complex Sample table in Oracle e-Business Suite (ERP) https://dataedo.com
- 7. Databases are large Number of tables and views in sample applications: • Sample custom enterprise application: 3,000 • TETA (HRM): 9,000 • Oracle e-Business Suite (ERP): 55,000 • SAP (ERP): 130,000! https://dataedo.com
- 8. …but as if addresses had following format: PA_ADW_R_ACT_CMT_B_V.TXN_ADW_NOTIFY_FLAG Finding a column is like trying to find an apartment in Manhattan
- 9. You need a map https://dataedo.com
- 10. When is it useful? • Software Development • Data Warehousing, BI • Data Analysis, Data Science, Big Bata • Packaged application implementation – ERP, CRM, HRM, billing etc. • Application Integration (EAI, EII, MDM) • Software/system maintenance • Data Migration • Data Quality • Master Data Management https://dataedo.com
- 11. II. WHAT IS DATABASE DOCUMENTATION
- 12. 1. Data Dictionary Table: employee Table holds past, current and future company employees. Column Data type Description BusinessEntityID int Primary key for Employee records. Foreign key to BusinessEntity.BusinessEntityID. NationalIDNumber nvarchar(15) Unique national identification number such as a social security number. LoginID nvarchar(256) Network login. OrganizationNode hierarchyid Where the employee is located in corporate hierarchy. OrganizationLevel smallint The depth of the employee in the corporate hierarchy. JobTitle nvarchar(50) Work title such as Buyer or Sales Representative. https://dataedo.com
- 13. Relations https://dataedo.com Table Role Foreign key column Description Departments Works in DepartmentID Department where emplyee People Manager ManagerID Employee superior JobsDict Job title TitleID Employee job title
- 14. Statuses Employee row can be in following statuses based on dates: • Future – start_date > today or start_date null • Current – start_date <= today and (end_date > today or null) • Past – end_date < today https://dataedo.com
- 15. List of Values Column Description MaritalStatus M = Married, S = Single, NULL = Unknown ActiveFlag 1 = Active, 0 = Inactive https://dataedo.com
- 16. Data Access Interface To modify and fetch data use this: • employee_get – returns specified employee row • employees_get – returns selected employees • employee_insert – use this to insert new employee • employee_update – use this to update employee row • employee_delete – use this to delete employee https://dataedo.com
- 17. Usage View: employees_active_v Used by: Employees search form, Active employees report https://dataedo.com
- 18. Data Source Table: employee Data source: Employees form, sync_employees Column Source MaritalStatus Employees form NationalIDNumber Employees form Number emp_no trigger Score Data warehouse, calc_employees_scores https://dataedo.com
- 19. Other Metadata Table: po_headers_all (Purchase orders) Subject Area: Purchasing Owner: Piotr Kononow Column po_header_id po_header_number [OBSOLETE] po_header_code qty Quantity value qty * unit_price https://dataedo.com
- 20. Meaningful Descriptions Instead of this: Column Description number Invoice number date Invoice date https://dataedo.com
- 21. Meaningful Descriptions Do this: Column Description number Invoice autogenerated number, starting from 1 each year. Number is generated when invoice gets approved. date Invoice issue date. Null for working copy invoices. Set to today’s date on invoice approval. https://dataedo.com
- 22. 2. ERDs – The Good https://dataedo.com
- 23. ERDs – The Bad https://dataedo.com
- 24. ERD is not this: https://dataedo.com
- 29. Rule of thumb: Document as you design and develop https://dataedo.com
- 30. What tools to use? • MS Excel, MS Word, Notepad • Database console • Dedicated tool https://dataedo.com
- 31. Database console – Description Not most convenient https://dataedo.com
- 32. Dedicated tools • Dataedo • Redgate SQL Doc • ApexSQL Doc https://dataedo.com
- 35. Thank you Piotr Kononow Learn more at: https://dataedo.com/blog