Description of investigation techniques

In order to improve a database performace or accuracy, an inital number of tests would be made on the customer data, normally using SQL scripting to verify the distinctness, cardinality and adherence to constraints. Table joins would be tested for orpaned data (unreferenced data), test-join SQL would select known correct data to prove join validity.

Summaries of table information would be matched against expected results. EG: product codes, accounts, addresses. This is normally assessed the customer, who can compare the expected and actual quantities. A backup copy of the data is normally made before an update script is run to produce correct the data. .

Quality issues may arise because of the accumulation of different data at different times, using various select-option lists. (This often shows up, for example, with address lines being accumulated in one or more columns depending on the persons training. -this would meandn printing address would look different for the different entires, or SQL queries would select different records demoending on the columns defined). Update proceedural changes may need to be reflected in historical data that is still important.



At the end of a contract, all programs, all scripts and other database objects are fully documented and suplied so that any further updates can be made using similar code at a later date.

Examples of Projects