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SQL First Row Selection Methods
geeksforgeeks.org/sql/how-to-select-the-first-row-of-each-group-by-in-sql/Yapay zekadan makale özeti
- Introduction
- SQL GROUP BY queries organize data into logical groups
- Window functions help isolate first row from each group
- Method 1: Aggregate Functions
- Uses MIN() or MAX() functions with GROUP BY clause
- Example finds earliest start date for each user
- Method 2: ROW_NUMBER() Window Function
- Assigns unique numbers to each row within group
- First row gets ROW_NUMBER=1
- Outer query filters results to include only first row
- Method 3: Column Selection
- Can return specific columns using comma-separated list
- Reduces data load and improves query performance
- Conclusion
- Multiple methods available for selecting first row of each group
- Each method has unique advantages based on use case