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        • EXPRESSION - Expression Function
        • EXPR - Expression Function (Abbreviation)
        • Incremental Calculation Explanation
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目录

Expression Functions

# StreamSQL Expression Functions

Expression functions are used for dynamic expression calculation.

# EXPRESSION - Expression Function

Syntax: expression(expr_str)
Description: Dynamically calculates an expression string.
Incremental Calculation: Not Supported
Example:

SELECT expression('price * quantity') as total FROM orders
1

# EXPR - Expression Function (Abbreviation)

Syntax: expr(expr_str)
Description: Dynamically calculates an expression string (abbreviated form of EXPRESSION).
Incremental Calculation: Not Supported
Example:

SELECT expr('temperature > 30') as is_hot FROM sensors
1

# Incremental Calculation Explanation

# Performance Advantages

Functions that support incremental calculation have significant performance advantages in stream processing:

  • Memory Efficiency: No need to save historical data
  • Calculation Efficiency: Avoids repeated calculations
  • Real-time: Results are updated in real-time

# Custom Function Extension

To extend more functions, please refer to:

  • Custom Function Development Guide
  • Plugin Development Documentation

# 📚 Related Documentation

  • Multi-row Functions - Learn detailed usage of multi-row functions
  • Aggregate Functions - Learn detailed usage of aggregate functions
  • SQL Reference - View complete SQL syntax reference
Edit this page on GitHub (opens new window)
Last Updated: 2025/08/05, 02:24:31
Multi-row Functions
Custom Functions

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