Difference between the HAVING and WHERE statements

Question

What is the difference between the HAVING and WHERE statements in SQL Server

Sandhiya Priya · Answer

Answer: The main difference between WHERE and HAVING in SQL Server is: WHERE Filters rows before grouping happens. Can be used with any column in the table (raw data). Cannot be used with aggregate functions like COUNT() , SUM() , etc. HAVING Filters rows after grouping has been done using GROUP BY . Is mainly used with aggregate functions to filter grouped results. Can also be used without GROUP BY (acts like a WHERE in that case). Example: -- WHERE filters before grouping SELECT Department, COUNT(*) AS EmployeeCount FROM Employees WHERE Department 'HR' -- filter before grouping GROUP BY Department; -- HAVING filters after grouping SELECT Department, COUNT(*) AS EmployeeCount FROM Employees GROUP BY Department HAVING COUNT(*) > 5; -- filter after grouping Execution Order in SQL Server: FROM WHERE (filters raw rows) GROUP BY (groups remaining rows) HAVING (filters grouped data) SELECT ORDER BY Summary Table: Feature WHERE HAVING Filters Before Grouping Yes No Filters After Grouping No Yes Works with Aggregates No Yes Requires GROUP BY No No (optional) In short: Use WHERE to filter rows before grouping. Use HAVING to filter grouped results, especially when using aggregate functions.

Cynthia Sathuragiri · Answer

Using WHERE -> Filter rows before aggregation SELECT Product, SUM(Quantity) AS TotalQty FROM Sales WHERE Quantity > 10 GROUP BY Product This only groups rows where Quantity > 10 (ignores rows ≤ 10). Using HAVING -> Filter after aggregation SELECT Product, SUM(Quantity) AS TotalQty FROM Sales GROUP BY Product HAVING SUM(Quantity) > 20 This groups all rows first then shows only products where the total quantity is more than 20.

Difference between the HAVING and WHERE statements

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