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
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# 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
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# 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:
# 📚 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
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Last Updated: 2025/08/05, 02:24:31