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MySQL equal operator

equal operator

MySQL equal operator performs an equality comparison.

Syntax:

=

MySQL Version: 5.6

Example: MySQL equal operator

The following MySQL statement checks if 1 is equal to 1, if 1 is equal to 2, if NULL is equal to NULL, if NULL is equal to 3 and if 3 is equal to NULL.

Code:

SELECT 1 = 1, 1=2,NULL = NULL, NULL=3,3= NULL;

Sample Output:

mysql> SELECT 1 = 1, 1=2,NULL = NULL, NULL=3,3= NULL;
+-------+-----+-------------+--------+---------+
| 1 = 1 | 1=2 | NULL = NULL | NULL=3 | 3= NULL |
+-------+-----+-------------+--------+---------+
|     1 |   0 |        NULL |   NULL |    NULL | 
+-------+-----+-------------+--------+---------+
1 row in set (0.00 sec)

Example: MySQL equal operator with WHERE clause

The following MySQL statement will fetch the rows after checking whether the publisher belongs to the USA.

Code:

SELECT pub_name,country,pub_city,estd
FROM publisher           
WHERE country='USA';

Relational Algebra Expression:

Relational Algebra Expression: MySQL equal operator with WHERE clause.

Relational Algebra Tree:

Relational Algebra Tree: MySQL equal operator with WHERE clause.

Sample table: publisher


Sample Output: 

mysql> SELECT pub_name,country,pub_city,estd
    -> FROM publisher           
    -> WHERE country='USA';
+--------------------------+---------+----------+------------+
| pub_name                 | country | pub_city | estd       |
+--------------------------+---------+----------+------------+
| Jex Max Publication      | USA     | New York | 1969-12-25 | 
| Mountain Publication     | USA     | Houstan  | 1975-01-01 | 
| Summer Night Publication | USA     | New York | 1990-12-10 | 
+--------------------------+---------+----------+------------+
3 rows in set (0.00 sec)

PHP script:

<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>example-equal-operator- php mysql examples | w3resource</title>
<meta name="description" content="example-equal-operator- php mysql examples | w3resource">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
</head>
<body>
<div class="container">
<div class="row">
<div class="col-md-12">
<h2>A list of the publishers who belog to USA. List also includes their date of country,city, date of establishment:</h2>
<table class='table table-bordered'>
<tr>
<th>Publishers</th><th>Country</th><th>City</th><th>Date of establishment</th>
</tr>
<?php
$hostname="your_hostname";
$username="your_username";
$password="your_password";
$db = "your_dbname";
$dbh = new PDO("mysql:host=$hostname;dbname=$db", $username, $password);
foreach($dbh->query('SELECT pub_name,country,pub_city,estd
FROM publisher
WHERE country="USA"') as $row) {
echo "<tr>";  
echo "<td>" . $row['pub_name'] . "</td>";
echo "<td>" . $row['country'] . "</td>";
echo "<td>" . $row['pub_city'] . "</td>";
echo "<td>" . $row['estd'] . "</td>";
echo "</tr>";
}
?>
</tbody></table>
</div>
</div>
</div>
</body>
</html>

View the example in browser

JSP script:

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>example-equal-operator</title>
</head>
<body>
<%
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
String Host = "jdbc:mysql://localhost:3306/w3resour_bookinfo";
Connection connection = null;
Statement statement = null;
ResultSet rs = null;
connection = DriverManager.getConnection(Host, "root", "datasoft123");
statement = connection.createStatement();
String Data ="SELECT pub_name,country,pub_city,estd FROM publisher WHERE country='USA'";
rs = statement.executeQuery(Data);
%>
<TABLE border="1">
<tr width="10" bgcolor="#9979">
<td>Publisher</td>
<td>Country</td>
<td>City</td>
<td>Date of establishment</td>
</tr>
<%
while (rs.next()) {
%>
<TR>
<TD><%=rs.getString("pub_name")%></TD>
<TD><%=rs.getString("country")%></TD>
<TD><%=rs.getString("pub_city")%></TD>
<TD><%=rs.getString("estd")%></TD>
</TR>
<%   }    %>
</table>
<%
rs.close();
statement.close();
connection.close();
} catch (Exception ex) {
out.println("Can’t connect to database.");
}
%>
</body>
</html>

Online Practice Editor:


Slideshow of MySQL Comparison Function and Operators

MySQL Comparison Function and Operators, slide presentation

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