What is SQL JOIN and why is it important for BAs?

Question

Accepted Answer

**SQL JOIN** — combining rows from two or more tables.

**Types:**
- **INNER JOIN** — matching rows only.
- **LEFT JOIN** — all from left, matching from right.
- **RIGHT JOIN** — all from right, matching from left.
- **FULL JOIN** — all rows from both.

**Example:**
```sql
SELECT customers.name, orders.total
FROM customers
INNER JOIN orders ON customers.id = orders.customer_id;

SELECT customers.name, orders.total
FROM customers
LEFT JOIN orders ON customers.id = orders.customer_id;
-- Shows all customers, even without orders
```

**Why BA needs it:**
- Query related data.
- Validate data relationships.
- Create reports.
- Understand data model.

Business Analyst: What is SQL JOIN and why is it important for BAs?