Working with Uniface can be challenging, especially when dealing with data deletion operations. Today, I'm diving deep into the erase command in Uniface 10.4 - one of the most powerful yet potentially dangerous operations you can perform! 💣
Note: This post is based on the official Uniface Documentation 10.4, and I had some assistance from AI to organize this comprehensive guide.
🎯 What is the Erase Command?
The erase statement in Uniface activates delete or deleteUp triggers for all occurrences in a component. Think of it as the nuclear option for data deletion - it's powerful, but you need to handle it with care! ⚠️
📝 Basic Syntax
erase{/e {Entity}}
🛠️ Key Features & Qualifiers
The /e Qualifier
The /e qualifier is your friend when you need to target specific entities:
- ✅ Erases all occurrences of the specified Entity
- 🔗 Includes inner entities if Cascading Delete relationship exists
- 🎯 Provides more granular control over what gets deleted
📊 Return Values You Need to Know
Understanding return values is crucial for error handling! Here are the most important ones:
| Value | Meaning | Action Required |
|---|---|---|
| 0 | ✅ Success | Data successfully erased |
| 1 | 🚫 Not allowed | Check component activation mode |
| -2 | 📭 Empty table | No data to erase |
| -6 | 💾 I/O error | Check disk space, permissions, constraints |
| -11 | 🔒 Already locked | Wait or handle concurrency |
🔗 Relationship Handling
The erase command behaves differently based on your entity relationships:
🌊 Cascading Delete
Related entities get deleted automatically - like a domino effect! 🎯
🚫 Nullify Delete
Foreign keys in related entities become null - safer but requires cleanup 🧹
⛔ Restricted Delete
Erase fails if related entities exist - your safety net! 🛡️
💡 Pro Tips for Safe Usage
1. Always Ask for Confirmation
trigger erase ; of component
if ($totocc(CUSTOMER) >= 1)
askmess "%%$totocc(CUSTOMER) occurrences. Erase them all?"
if ($status = 0)
return
endif
endif
erase
2. Handle Errors Gracefully
if ($status < 0)
message "Erase error; see message frame"
rollback
else
if ($status = 1)
message "Erase is not allowed"
else
message "Erase was successful"
commit
endif
endif
3. For Complete Database Deletion
Need to delete everything? Use this pattern:
setocc "*",-1 ; Retrieve all occurrences
erase ; Then erase them
⚠️ Critical Warning
The erase command only deletes fetched occurrences! If you haven't retrieved data into your component, it won't be deleted. This is both a safety feature and a potential gotcha! 🎭
🚀 Best Practices
- 🔍 Always validate data before erasing
- 💾 Use transactions (commit/rollback)
- 📝 Log important deletions
- 🧪 Test thoroughly in development
- 👥 Consider user permissions and roles
- 📊 Monitor performance with large datasets
🎬 Conclusion
The Uniface erase command is incredibly powerful for bulk data operations, but with great power comes great responsibility! 🕷️ Always implement proper safeguards, error handling, and user confirmations.
Remember: it's much easier to prevent accidental data loss than to recover from it! 💪
Happy coding, and may your erases be intentional! 🎯✨
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