SQL WHERE Clause

The `WHERE` clause in SQL is used to filter records and fetch only those rows that satisfy a specified condition. It is used with SQL statements like `SELECT`, `UPDATE`, and `DELETE`.

Syntax

The basic syntax of the `WHERE` clause is as follows:


                SELECT column1, column2, ...

                FROM table_name

                WHERE condition;

Example

Suppose you have a table named Employees with a column named Age. To get the records of employees who are 30 years old, you would use the following query:


                SELECT *

                FROM Employees

                WHERE Age = 30;

Operators

The `WHERE` clause can use various operators to filter records. Some common operators include:

= - Equal to
WHERE column = value
<> - Not equal to
WHERE column <> value
> - Greater than
WHERE column > value
< - Less than
WHERE column < value
BETWEEN - Within a range
WHERE column BETWEEN value1 AND value2
LIKE - Pattern matching
WHERE column LIKE pattern
IN - Match any value in a list
WHERE column IN (value1, value2, ...)

Notes

Case Sensitivity: In SQL, string comparisons can be case-sensitive or case-insensitive, depending on the database system.
Combining Conditions: You can combine multiple conditions using operators like AND, OR, and NOT to filter records more precisely.

Understanding how to use the `WHERE` clause effectively will allow you to filter data according to your needs, making your queries more precise and efficient.