MySQL WHERE

The MySQL WHERE Clause

The WHERE clause filters records based on specified conditions, extracting only those that meet the criteria.

WHERE Syntax

SELECT column1, column2, …
FROM table_name
WHERE condition;

Note: The WHERE clause is not exclusive to SELECT statements; it is also utilized in UPDATE, DELETE, and other SQL operations.

Demo Database

Here is an excerpt from the “Customers” table in the Northwind sample database:

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

WHERE Clause Example

The SQL statement below retrieves all customers located in “Mexico”:

Example

SELECT * FROM Customers
WHERE Country = ‘Mexico’;

Text Fields vs. Numeric Fields

SQL necessitates single quotes for text values (with some database systems also accepting double quotes), while numeric fields should not be enclosed in quotes.

Example

SELECT * FROM Customers
WHERE CustomerID = 1;

Operators in The WHERE Clause

The following operators are applicable within the WHERE clause:

Operator	Description
=	Equal
>	Greater than
<	Less than
>=	Greater than or equal
<=	Less than or equal
<>	Not equal. Note: In some SQL versions, this operator can also be represented as !=
BETWEEN	Within a specified range
LIKE	To search for a specific pattern
IN	To specify multiple potential values for a column