What does where mean in sql?

<blockquote><p>The WHERE clause is used to filter data from a table by selecting specific rows based on specified conditions. Conditions can be a combination of column names, operators, and constants, and conditions can be combined using the AND and OR operators. Benefits include improved query performance, data accuracy, and flexibility. </p></blockquote> <p><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/202404/29/2024042914421417407.jpg" class="lazy" alt="What does where mean in sql?" ></p> <p><strong>Usage of WHERE clause in SQL</strong></p> <p>The WHERE clause is used to filter data from a table. It allows you to select specific rows or records based on specified criteria. </p> <p><strong>Syntax: </strong></p> <div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false"><code>SELECT * FROM table_name WHERE condition;</code></pre><div class="contentsignin">Copy after login</div></div> <p><strong>Conditions: </strong></p> <p>Conditions are expressions used to filter data. It can be a combination of column names, operators, and constants. </p> <p><strong>Operators: </strong></p> <p>Commonly used operators include: </p> <ul> <li> is equal to (<code>=</code>)</li> <li>Not equal to (<code><></code>)</li> <li>Greater than (<code>></code>)</li> <li>Less than (<code><</code>) </li><li>Greater than or equal to (<code>>=</code>)</li> <li>Less than or equal to (<code><=</code>)</li></ul><p><strong> AND and OR: </strong></p><p>You can combine conditions using the <code>AND</code> and <code>OR</code> operators. </p><ul><li><code>AND</code> operator returns rows that satisfy all conditions. </li><li><code>OR</code> operator returns rows that satisfy any condition. </li></ul><p><strong>Example: </strong></p><p>The following is a query that selects all customers older than 25 years old from a table named "customers": </p><pre class="brush:php;toolbar:false"><code>SELECT * FROM customers WHERE age > 25;</code> <p><strong>Benefits of using the WHERE clause: </strong></p> <p>The WHERE clause provides the following benefits: </p> <ul> <li>Improving query performance by filtering unnecessary data Reduce processing time. </li> <li>Improve data accuracy and ensure correct results are returned by selecting only rows that meet specified conditions. </li> <li> Improve query flexibility, allowing you to dynamically filter data as needed. </li> </ul> </li> </ul>

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