Understanding the Difference: WHERE vs HAVING in SQL

In SQL, the difference between WHERE and HAVING clauses is when they filter data in the query process:

• WHERE is used to filter records before aggregation. It applies to individual rows in the dataset.
• HAVING is used to filter records after aggregation. It applies to the results of aggregate functions, such as SUM, AVG, COUNT, etc.

To avoid unexpected results in SQL when using the same column alias for an aggregated column as in the input table, it's recommended to:

• Rename the aggregated column to something more descriptive, like total_quantity instead of just quantity.
• This helps differentiate between the original column and the aggregated result, ensuring clarity in your SQL queries.