The difference between where and having in sql

The WHERE clause is used to filter the rows of the query results (for individual rows), while the HAVING clause is used to filter the groups produced by the GROUP BY clause (for the aggregated values ​​in the group).

The difference between the WHERE clause and the HAVING clause in SQL

The WHERE clause and the HAVING clause are both Conditions used in SQL to filter data, but they apply to different data levels:

WHERE clause

• Applies to a single row in the data set
• Used to filter individual rows of query results
• Apply conditions to specific column values ​​in rows
• Use before the GROUP BY clause

HAVING clause

• Applies to groups generated by the GROUP BY clause
• Used to filter groups created based on the GROUP BY clause
• Apply conditions to aggregate values ​​in a group (e.g., SUM, COUNT, etc.)
• Use after the GROUP BY clause

Example

WHERE clause:

<code class="sql">SELECT * FROM customers WHERE age > 25;</code>

This query will return all customer rows with an age greater than 25.

HAVING clause:

<code class="sql">SELECT region, COUNT(*) AS total_orders
FROM orders
GROUP BY region
HAVING total_orders > 100;</code>

This query will return zone groups where the total number of orders exceeds 100.

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