MySQL не является пустым оператором
Оператор NOT NULL
Оператор MySQL IS NOT NULL проверит, не является ли значение NULL.
Синтаксис:
НЕ НУЛЬ
Версия MySQL: 5.6
Пример: MySQL не является оператором NULL
В следующем операторе MySQL проверяется, не являются ли 5, 0 и NULL NULL.
Код:
SELECT 5 IS NOT NULL,0 IS NOT NULL, NULL IS NOT NULL;
Пример вывода:
mysql> SELECT 5 NOT NULL, 0 NOT NULL, NULL НЕ NULL; + --------------- + --------------- + ----------------- - + | 5 НЕ НУЛЬ | 0 НЕ НУЛЬ | NULL НЕ NULL | + --------------- + --------------- + ----------------- - + | 1 | 1 | 0 | + --------------- + --------------- + ----------------- - + 1 ряд в наборе (0,00 сек)
PHP скрипт
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>example-is-not-null- php mysql examples | w3resource</title>
<meta name="description" content="example-is-not-null- 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>Checking whether a value IS NOT NULL using MySQL:</h2>
<table class='table table-bordered'>
<tr>
<th>5 IS NOT NULL</th><th>0 IS NOT NULL</th><th>NULL IS NOT NULL</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 5 IS NOT NULL,0 IS NOT NULL, NULL IS NOT NULL') as $row) {
echo "<tr>";
echo "<td>" . $row['5 IS NOT NULL'] . "</td>";
echo "<td>" . $row['0 IS NOT NULL'] . "</td>";
echo "<td>" . $row['NULL IS NOT NULL'] . "</td>";
echo "</tr>";
}
?>
</tbody></table>
</div>
</div>
</div>
</body>
</html>
JSP скрипт
<%@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-is-not-null</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 5 IS NOT NULL,0 IS NOT NULL, NULL IS NOT NULL";
rs = statement.executeQuery(Data);
%>
<TABLE border="1">
<tr width="10" bgcolor="#9979">
<td>5 IS NOT NULL</td>
<td>0 IS NOT NULL</td>
<td>5 IS NOT NULL</td>
</tr>
<%
while (rs.next()) {
%>
<TR>
<TD><%=rs.getString("5 IS NOT NULL")%></TD>
<TD><%=rs.getString("0 IS NOT NULL")%></TD>
<TD><%=rs.getString("NULL IS NOT NULL")%></TD>
</TR>
<% } %>
</table>
<%
rs.close();
statement.close();
connection.close();
} catch (Exception ex) {
out.println("Can’t connect to database.");
}
%>
</body>
</html>
Слайд-шоу функции сравнения MySQL и операторов
Предыдущая: ИНТЕРВАЛ ()
Далее: НЕТ
Новый контент: Composer: менеджер зависимостей для PHP , R программирования
disqus2code