Difference Between WHERE and HAVING Clause in SQL for Oracle

When writing SQL queries in Oracle, it is important to understand the differences between the WHERE and HAVING clauses. Both clauses are used to apply conditions to select data, but they serve distinct purposes.

WHERE Clause:

The WHERE clause is used to filter records based on a specified condition. It is applied to individual rows before they are grouped or aggregated. This means that the WHERE clause is used to filter data at the row-level.

HAVING Clause:

The HAVING clause, on the other hand, is used to filter records based on group-level conditions. It is applied after the data has been grouped using the GROUP BY clause. The HAVING clause is used to filter aggregated data based on conditions.

Key Differences:

• The WHERE clause is used for row-level filtering, while the HAVING clause is used for group-level filtering.
• WHERE clause is applied before data is grouped, while the HAVING clause is applied after data is grouped.
• Use the WHERE clause to filter individual rows based on conditions, and use the HAVING clause to filter grouped data based on aggregate functions.

By understanding the differences between the WHERE and HAVING clauses in SQL queries for Oracle, you can effectively use them to retrieve the desired data based on specific criteria.