How does HAVING differ from WHERE?

The HAVING clause and the WHERE clause are both used to filter records in SQL, but they serve different purposes and are used at different stages of query execution:

1. WHERE Clause:

   • Used to filter records before any groupings are made.
   • It cannot be used with aggregate functions directly.
   • Example:

     SELECT column_name
     FROM table_name
     WHERE condition;

2. HAVING Clause:

   • Used to filter records after the aggregation has been performed.
   • It can be used with aggregate functions.
   • Example:

     SELECT column_name, COUNT(*)
     FROM table_name
     GROUP BY column_name
     HAVING COUNT(*) > 1;

In summary, use WHERE to filter rows before aggregation and HAVING to filter groups after aggregation.