SQL WHERE Clause

The WHERE clause is used to filter records.

It is used to extract only those records that fulfill a specified condition.

SELECT column1, column2, ...
FROM table_name
WHERE condition;

Note: The WHERE clause is not only used in SELECT statements, it is also used in UPDATE, DELETE, etc.!

SQL requires single quotes around text values (most database systems will also allow double quotes).

However, numeric fields should not be enclosed in quotes:

SELECT * FROM Customers WHERE Country='Mexico'; -- Correct (Text)
SELECT * FROM Customers WHERE CustomerID=1;     -- Correct (Number)

The following operators can be used in the WHERE clause:

= Equal
> Greater than
< Less than
>= Greater than or equal
<= Less than or equal
<> Not equal. Note: In some versions of SQL this operator may be written as !=
BETWEEN Between a certain range
LIKE Search for a pattern
IN To specify multiple possible values for a column

SQL Where