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-- View all client orders
SELECT *
FROM client_orders;

-- Use WHERE to filter individual rows before grouping
SELECT client_name, region, order_total
FROM client_orders
WHERE region = 'USA';

-- Use HAVING to filter groups after aggregation
SELECT region, AVG(order_total) AS avg_order
FROM client_orders
GROUP BY region
HAVING AVG(order_total) > 200;

# `WHERE` vs `HAVING`

In this lesson, you’ll explore the difference between `WHERE` and `HAVING`.

Both clauses are used to **filter data**, but they work at different stages of a SQL query.

<br/>

## `WHERE`: Filter Rows Before Aggregation

The `WHERE` clause filters individual rows before any aggregation or grouping happens.

```sql title="Filter before grouping"
SELECT client_name, region, order_total
FROM client_orders
WHERE region = 'USA';
```

This query returns all orders placed by clients in the USA.

<br/>

## `HAVING`: Filter After Grouping

The `HAVING` clause filters **groups** after aggregation and is typically used with `GROUP BY`.

```sql title="Filter groups after aggregation"
SELECT region, AVG(order_total) AS avg_order
FROM client_orders
GROUP BY region
HAVING AVG(order_total) > 200;
```

This query returns regions where the average order total exceeds 200.

<br/>

## Summary: When to Use Each

| Clause   | Filters...               | Works With Aggregates?     |
| -------- | ------------------------ | -------------------------- |
| `WHERE`  | Individual rows          | ❌ Not used with aggregates |
| `HAVING` | Groups after aggregation | ✅ Yes                      |

- Use `WHERE` for raw row-level filters.
- Use `HAVING` when filtering aggregated results.

The HAVING clause is specifically used to filter records after they have been grouped and aggregated. While WHERE is used before aggregation to filter rows, HAVING comes into play after the aggregation, allowing you to apply conditions to grouped results. This distinction is vital when working with aggregate functions like SUM, AVG, etc.

### In SQL, which clause would you use to filter groups after an aggregation has been applied?

Clause	Filters...	Works With Aggregates?
`WHERE`	Individual rows	❌ Not used with aggregates
`HAVING`	Groups after aggregation	✅ Yes

WHERE vs HAVING

WHERE: Filter Rows Before Aggregation

HAVING: Filter After Grouping

Summary: When to Use Each

In SQL, which clause would you use to filter groups after an aggregation has been applied?

`WHERE` vs `HAVING`

`WHERE`: Filter Rows Before Aggregation

`HAVING`: Filter After Grouping