6.5 Using Page Items for Query by Example

Page items, including list-driven ones, are useful not only for data entry, but also for query by example use cases. The user can enter a value or pick a choice from a list, and another region on the same page can filter its data based on their choice.

You accomplish this by referencing page item values in the other region's WHERE clause. When you use page items values as query by example filters, you can also easily disable the default warning the user receives when leaving the page with unsaved pending changes.

• Using Null Display Value
  When using the Select List, Radio Group, and Popup LOV you can optionally include an item in the list that represents the null value, and if included it can have a custom label.
• Filtering on a Page Item's Value
  You can use any page item's value in a query filter in another region. Most page item types, including single-selection list-driven items, store just one value that can also be null.
• Filtering on a Multi-Selection Page Item
  When a query-by-example item allows multiple selection, filtering by its value requires an IN clause with a subquery.
• Optimal Approach to Query by Example
  Two approaches exist for query-by-example WHERE clause filters. One requires less typing; the other performs better.
• Disabling Warn on Unsaved Changes
  Query-by-example items change values by design. Disable the unsaved changes warning so users aren't confused when navigating away.