问题
I have a set of text Field items in Oracle Apex:
- Order Number
- Revision Number
When we open the report, revision should be hidden.
Only when the user enters unique order number (non-duplicate order numbers), revision number should be visible.
If he enters duplicate order number, revision number should be hidden.
回答1:
A simple (though not bullet-proof) solution is to create a Dynamic Action on the Order Number item that, when Changed, issues a query on the database to check if the order number already exists; if found, it hides the Revision Number item, otherwise it shows it.
You would want to ensure there is a suitable index on the order number column on the database so that the query returns as fast as possible.
If two people are in the screen at the same time, and enter the same order number, the query will not see the order number so this method is not guaranteed to always work perfectly.
来源：https://stackoverflow.com/questions/29743964/how-to-hide-text-field-item-based-on-true-or-false-cases-in-oracle-apex