How do I use two WHERE clauses in SQL?

In SQL, you don't use two separate WHERE clauses in a single query. Instead, you combine multiple conditions within a single WHERE clause using logical operators such as AND, OR, and NOT. Here's how you can effectively use multiple conditions:

1. Using the `AND` Operator:

- The AND operator requires that both conditions on either side of it must be true for a row to be included in the result set.

- Example: To select all customers from the 'Customers' table who are from 'London' and have an order amount greater than 100:

SELECT
FROM Customers
WHERE City = 'London' AND OrderAmount > 100;

2. Using the `OR` Operator:

- The OR operator requires that at least one of the conditions on either side of it must be true for a row to be included in the result set.

- Example: To select all customers from the 'Customers' table who are from 'London' or have an order amount greater than 100:

SELECT
FROM Customers
WHERE City = 'London' OR OrderAmount > 100;

3. Combining `AND` and `OR` Operators:

- You can combine AND and OR operators in a single WHERE clause. Use parentheses to control the order of evaluation.

- Example: To select all customers from the 'Customers' table who are from 'London' and have an order amount greater than 100, or who are from 'Paris':

SELECT
FROM Customers
WHERE (City = 'London' AND OrderAmount > 100) OR City = 'Paris';

4. Using the `NOT` Operator:

- The NOT operator negates a condition. It returns true if the condition is false, and vice versa.

- Example: To select all customers from the 'Customers' table who are not from 'London':

SELECT
FROM Customers
WHERE NOT City = 'London';

Key Points:

- Always use logical operators (AND, OR, NOT) to combine multiple conditions within a single WHERE clause.

- Use parentheses to clarify the order of operations when combining AND and OR operators.

- Avoid using multiple WHERE clauses in a single SQL query; it's not the correct syntax.

By understanding how to use these logical operators, you can create complex and precise queries to retrieve the exact data you need from your database.

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