SQL WHERE Clause

The WHERE clause in SQL is used to filter rows from a table based on specified conditions.

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1. Overview

The WHERE clause is an essential part of SQL statements, allowing users to retrieve only the rows that meet specific criteria.

Example:

// Example of using the WHERE clause
SELECT *
FROM employees
WHERE department = 'IT';

In this example, the WHERE clause filters rows from the employees table where the department is 'IT'.

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2. Syntax

The basic syntax of the WHERE clause is as follows:

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

The condition can include comparisons, logical operators, and functions to specify the filtering criteria.

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3. Usage

To use the WHERE clause, specify the condition after the WHERE keyword in an SQL statement.

Example:

// Example of using the WHERE clause with multiple conditions
SELECT *
FROM orders
WHERE order_date >= '2022-01-01' AND order_date <= '2022-12-31';

This example retrieves all columns from the orders table where the order_date falls within the year 2022.

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4. Conclusion

The SQL WHERE clause is a powerful tool for filtering data in SQL queries, allowing users to retrieve only the relevant rows from a table based on specified conditions. Understanding how to use the WHERE clause effectively is essential for querying and manipulating data in databases.