007 SQL AND

The page explains the SQL AND operator and its use in filtering records with multiple conditions in a SQL query.

Purpose: The AND operator is used in the WHERE clause to select records only when all conditions are true.

Syntax:

SELECT column1, column2, ...
FROM table_name
WHERE condition1 AND condition2 AND condition3 ...;

Example: To select all customers from Spain whose names start with 'G':

SELECT * FROM Customers
WHERE Country = 'Spain'
AND CustomerName LIKE 'G%';

AND vs. OR:
- AND returns a row only if all conditions are TRUE.
- OR returns a row if any condition is TRUE.
Combining AND and OR: Parentheses are recommended to ensure correct logic. For example:
```
SELECT * FROM Customers
WHERE Country = 'Spain'
AND (CustomerName LIKE 'G%' OR CustomerName LIKE 'R%');
```
Without parentheses, SQL may return customers who start with 'R' regardless of country.
Practice: There is an exercise at the end asking if AND is used to filter based on more than one condition (answer: True).
Resources: The page includes example queries and links to try them interactively.

In summary, the page is a practical guide on how to use the SQL AND operator to filter database results by requiring multiple conditions to be true.[1]

SQL AND Operator

The SQL AND Operator

The WHERE clause can contain one or many AND operators.

The AND operator is used to filter records based on more than one condition, like if you want to return all customers from Spain that starts with the letter 'G':

Select all customers from Spain that starts with the letter 'G':

SELECT *  
FROM Customers  
WHERE Country = 'Spain' AND CustomerName LIKE 'G%';

Syntax

SELECT column1, column2, ...
FROM table_name
WHERE condition1 AND condition2 AND condition3 ...;

AND vs OR

The AND operator displays a record if all the conditions are TRUE.

The OR operator displays a record if any of the conditions are TRUE.

Demo Database

Below is a selection from the Customers table used in the examples:

CustomerID	CustomerName	ContactName	Address	City	PostalCode	Country
1	Alfreds Futterkiste	Maria Anders	Obere Str. 57	Berlin	12209	Germany
2	Ana Trujillo Emparedados y helados	Ana Trujillo	Avda. de la Constitución 2222	México D.F.	05021	Mexico
3	Antonio Moreno Taquería	Antonio Moreno	Mataderos 2312	México D.F.	05023	Mexico
4	Around the Horn	Thomas Hardy	120 Hanover Sq.	London	WA1 1DP	UK
5	Berglunds snabbköp	Christina Berglund	Berguvsvägen 8	Luleå	S-958 22	Sweden

All Conditions Must Be True

The following SQL statement selects all fields from Customers where Country is "Brazil" AND City is "Rio de Janeiro" AND CustomerID is higher than 50:

SELECT * FROM Customers  
WHERE Country = 'Brazil'  
AND City = 'Rio de Janeiro'  
AND CustomerID > 50;

Combining AND and OR

You can combine the AND and OR operators.

The following SQL statement selects all customers from Spain that starts with a "G" or an "R".

Make sure you use parenthesis to get the correct result.

Select all Spanish customers that starts with either "G" or "R":

SELECT * FROM Customers  
WHERE Country = 'Spain' AND (CustomerName LIKE 'G%' OR CustomerName LIKE 'R%');

Without parenthesis, the select statement will return all customers from Spain that starts with a "G", plus all customers that starts with an "R", regardless of the country value:

Select all customers that either:
are from Spain and starts with either "G", or
starts with the letter "R":

SELECT * FROM Customers  
WHERE Country = 'Spain' AND CustomerName LIKE 'G%' OR CustomerName LIKE 'R%';