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881Introduction to Aggregate Functions
882COUNT: Counting Rows and Non-Null Values
883SUM: Calculating Totals
884AVG: Computing Averages
885MIN and MAX: Finding Extremes
886Combining Multiple Aggregate Functions
887Aggregates with DISTINCT
888Handling NULL Values in Aggregates
889Aggregate Functions Without GROUP BY
890Introduction to GROUP BY
891Single Column Grouping
892GROUP BY with Different Aggregate Functions
893ORDER BY with GROUP BY
894NULL Values in GROUP BY
895Combining WHERE and GROUP BY
896GROUP BY Execution Order
897Common GROUP BY Mistakes
898HAVING Clause Fundamentals
899HAVING vs WHERE: Key Differences
900Using HAVING with Aggregate Functions
901Multiple Conditions in HAVING
902HAVING with Complex Expressions
903Combining WHERE and HAVING
904Common HAVING Clause Patterns
905Grouping by Multiple Columns: Basics
906Order Matters: Column Sequence in GROUP BY
907Aggregating Across Multiple Dimensions
908Multi-Level Grouping in Business Analytics
909Combining Multiple Groups with SELECT
910Three or More Grouping Columns
911Performance Considerations with Multiple Groups
912Fundamental Difference: Filter Timing
913WHERE: Filtering Individual Rows
914HAVING: Filtering Aggregated Results
915Combining WHERE and HAVING
916Performance Implications
917Common Patterns and Anti-Patterns

881Introduction to Aggregate Functions
882COUNT: Counting Rows and Non-Null Values
883SUM: Calculating Totals
884AVG: Computing Averages
885MIN and MAX: Finding Extremes
886Combining Multiple Aggregate Functions
887Aggregates with DISTINCT
888Handling NULL Values in Aggregates
889Aggregate Functions Without GROUP BY
890Introduction to GROUP BY
891Single Column Grouping
892GROUP BY with Different Aggregate Functions
893ORDER BY with GROUP BY
894NULL Values in GROUP BY
895Combining WHERE and GROUP BY
896GROUP BY Execution Order
897Common GROUP BY Mistakes
898HAVING Clause Fundamentals
899HAVING vs WHERE: Key Differences
900Using HAVING with Aggregate Functions
901Multiple Conditions in HAVING
902HAVING with Complex Expressions
903Combining WHERE and HAVING
904Common HAVING Clause Patterns
905Grouping by Multiple Columns: Basics
906Order Matters: Column Sequence in GROUP BY
907Aggregating Across Multiple Dimensions
908Multi-Level Grouping in Business Analytics
909Combining Multiple Groups with SELECT
910Three or More Grouping Columns
911Performance Considerations with Multiple Groups
912Fundamental Difference: Filter Timing
913WHERE: Filtering Individual Rows
914HAVING: Filtering Aggregated Results
915Combining WHERE and HAVING
916Performance Implications
917Common Patterns and Anti-Patterns

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Lesson 882 of 2,145·23. SQL Aggregation and GroupingPro lesson

COUNT: Counting Rows and Non-Null Values

Using COUNT(*) to count all rows and COUNT(column) to count non-null values in a column.

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