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Mastering Uniface numgen: Generate Unique Sequence Numbers Like a Pro 🚀

#uniface #programming #database #development

Working with Uniface and need to generate unique sequence numbers? The numgen statement is your best friend! 💪 Let me walk you through everything you need to know about this powerful counter function. This post is based on the official Uniface documentation 10.4, and I had some AI assistance to structure this comprehensive guide.

What is numgen? 🤔

The numgen statement is Uniface's built-in solution for incrementing counters and generating unique sequence numbers. It's perfect for creating invoice numbers, order IDs, or any sequential identifiers in your applications.

Syntax and Parameters 📋 

numgen CounterName, Increment {, LibraryName}
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Parameters Breakdown:

  • CounterName (String): The name of your counter 🏷️
  • Increment (Number): How much to increment (range: -2,147,483,648 to 2,147,483,647) ➕
  • LibraryName (String, Optional): Counter library name (defaults to SYSTEM_LIBRARY) 📚

Return Values and Status Codes 📊

After executing numgen, you'll get:

  • $result: Contains the new incremented number ✨
  • $status: Indicates success or failure

Status Code Meanings:

Value Meaning Status
0 Counter successfully incremented ✅ Success
-1 Counter out of range or not defined ❌ Error
-2 Increment out of range ❌ Error

Practical Examples 💡

Example 1: Generating Invoice Numbers 

operation exec
numgen "INVOICE_NUMBER", 1, "COUNTER_LIB"
if ($status < 0)
    message "Error generating sequence number." 
    rollback "$UUU"
    edit SEQNO
    done
else
    SEQNO = $result
    commit "$UUU"
    edit NAME
endif
end; exec
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Example 2: Auto-generating IDs in Create Trigger 

trigger: create
if ($rettype = 65)
    creocc "INVOICE", $curocc + 1
else
    creocc "INVOICE", $curocc
endif

numgen "INV_COUNT", 1, $variation
INV_NUM/init = $result
commit "$UUU"
end; create
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Best Practices and Tips 🎯

1. Always Handle Errors

Check $status after every numgen call to ensure proper error handling 🛡️

2. Commit Immediately

Follow numgen with commit "$UUU" to avoid locking problems when multiple users access the same counter 🔒

3. Use Descriptive Counter Names

Names like "INVOICE_NUMBER" or "ORDER_ID" make your code more maintainable 📝

4. Leverage Libraries

Use different libraries to organize counters by project or module 🗂️

Common Pitfalls to Avoid ⚠️

  • Forgetting to commit: This can cause locking issues in multi-user environments
  • Not checking $status: Always verify the operation succeeded
  • Using in create triggers: Can result in lost sequence numbers if data isn't stored

Error Handling Reference 🔧

Common $procerror values you might encounter:

  • -2 to -12 (UIOSERR_*): Database I/O errors 💾
  • -16 to -30 (UNETERR_*): Network I/O errors 🌐
  • -1108 (UPROCERR_COUNTER): Repository access issues or undefined counter 🚫
  • -1203 (UPROCERR_RANGE): Value out of range error 📏

Conclusion 🎉

The numgen statement is an essential tool for any Uniface developer working with sequential data. By following the best practices outlined above, you'll be able to generate unique sequence numbers reliably and efficiently in your applications.

Remember: always handle errors gracefully, commit your counters promptly, and use descriptive names for better code maintainability! 🚀

Happy coding! 👨‍💻👩‍💻

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