MySQL 扩展概述范例

这个简单的范例展示了如何连接、执行一个查询，打印结果集后断开 MySQL 数据库的连接。

Example #1 MySQL 扩展概述范例

<?php
// 连接、选择数据库
$link = mysql_connect('mysql_host', 'mysql_user', 'mysql_password')
    or die('Could not connect: ' . mysql_error());
echo 'Connected successfully';
mysql_select_db('my_database') or die('Could not select database');

// 执行 SQL 查询
$query = 'SELECT * FROM my_table';
$result = mysql_query($query) or die('Query failed: ' . mysql_error());

// 以 HTML 打印查询结果
echo "<table>\n";
while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
    echo "\t<tr>\n";
    foreach ($line as $col_value) {
        echo "\t\t<td>$col_value</td>\n";
    }
    echo "\t</tr>\n";
}
echo "</table>\n";

// 释放结果集
mysql_free_result($result);

// 关闭连接
mysql_close($link);
?>

User Contributed Notes

zjrwjzzz at 163 dot com 13-Feb-2015 05:03
Be aware that if you are trying to foreach the associative array returned by mysql_fetch_array() with MYSQL_ASSOC or mysql_fetch_assoc(), you have to ensure the return value that is used in foreach structure is exactly a array rather than a FALSE value.

Or you might encounter the warning below:
    Warning: Invalid argument supplied for foreach()

Here is an example (assume that $result have already stored the return value from mysql_query()):

If you have some block of code like:

<?php

// Printing results in HTML
echo "<table>\n";
while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
    echo "\t<tr>\n";
    foreach ($line as $col_value) {
        echo "\t\t<td>$col_value</td>\n";
    }
    echo "\t</tr>\n";
}
echo "</table>\n";

?>

If this is the case, you should use the code below instead:

<?php

// Check ahead, before using it
if (mysql_num_rows($result) > 0) {
    // Printing results in HTML
    echo "<table>\n";
    while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
        echo "\t<tr>\n";
        foreach ($line as $col_value) {
            echo "\t\t<td>$col_value</td>\n";
        }
        echo "\t</tr>\n";
    }
    echo "</table>\n";
}

?>