What is difference between WHERE and HAVING in SQL Server?

Dung Do Tien Oct 19 2020 27

I only use WHERE clause to filter data but HAVING also use to filter data. Can anybody explain to me what is the difference between them? and when we should use them?

Have 1 answer(s) found.
  • I can note some difference between them as below:

    1. WHERE

    - Filter data from a result, usually filter columns available in the table. 

    - It filters before any groups are made.

    - Can't use the aggregate function to filter.

     

    2. HAVING

    - Used to filter values from a group.

    - Only use the aggregate function to filter.

    - Can't using HAVING if not use to the GROUP BY clause.

    - Performance is SLOW because the aggregate function needs to calculation.

    Marry Christ Oct 19 2020
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