php MySQL 查询数据

陌上傾寒 發表於 2019-7-10 15:40:00

以下为在MySQL数据库中查询数据通用的 SELECT 语法：
<div class="cnblogs_code">
<pre>SELECT column_name,column_name
FROM table_name

[ OFFSET M]</pre>
</div>
<h2 class="example">使用 mysqli_fetch_array MYSQLI_ASSOC 参数获取数据：</h2>
 
<div class="cnblogs_code">
<pre><?php
$dbhost = 'localhost:3306';// mysql服务器主机地址
$dbuser = 'root'; // mysql用户名
$dbpass = '123456'; // mysql用户名密码
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
die('连接失败: ' . mysqli_error($conn));
}
// 设置编码，防止中文乱码
mysqli_query($conn , "set names utf8");

$sql = 'SELECT runoob_id, runoob_title,
 runoob_author, submission_date
 FROM runoob_tbl';

mysqli_select_db( $conn, 'RUNOOB' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
die('无法读取数据: ' . mysqli_error($conn));
}
echo '<h2>菜鸟教程 mysqli_fetch_array 测试<h2>';
echo '<table border="1"><tr><td>教程 ID</td><td>标题</td><td>作者</td><td>提交日期</td></tr>';
while($row = mysqli_fetch_array($retval, MYSQLI_ASSOC))
{
echo "<tr><td> {$row['runoob_id']}</td> ".
 "<td>{$row['runoob_title']} </td> ".
 "<td>{$row['runoob_author']} </td> ".
 "<td>{$row['submission_date']} </td> ".
 "</tr>";
}
echo '</table>';
mysqli_close($conn);
?></pre>
</div>
<h2 class="example">使用 mysqli_fetch_assoc 获取数据：</h2>
<div class="cnblogs_code">
<pre><?php
$dbhost = 'localhost:3306';// mysql服务器主机地址
$dbuser = 'root'; // mysql用户名
$dbpass = '123456'; // mysql用户名密码
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
die('连接失败: ' . mysqli_error($conn));
}
// 设置编码，防止中文乱码
mysqli_query($conn , "set names utf8");

$sql = 'SELECT runoob_id, runoob_title,
 runoob_author, submission_date
 FROM runoob_tbl';

mysqli_select_db( $conn, 'RUNOOB' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
die('无法读取数据: ' . mysqli_error($conn));
}
echo '<h2>菜鸟教程 mysqli_fetch_assoc 测试<h2>';
echo '<table border="1"><tr><td>教程 ID</td><td>标题</td><td>作者</td><td>提交日期</td></tr>';
while($row = mysqli_fetch_assoc($retval))
{
echo "<tr><td> {$row['runoob_id']}</td> ".
 "<td>{$row['runoob_title']} </td> ".
 "<td>{$row['runoob_author']} </td> ".
 "<td>{$row['submission_date']} </td> ".
 "</tr>";
}
echo '</table>';
mysqli_close($conn);
?></pre>
</div>
<h2 class="example">使用 mysqli_fetch_array MYSQLI_NUM 参数获取数据：</h2>
<div class="cnblogs_code">
<pre><?php
$dbhost = 'localhost:3306';// mysql服务器主机地址
$dbuser = 'root'; // mysql用户名
$dbpass = '123456'; // mysql用户名密码
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
die('连接失败: ' . mysqli_error($conn));
}
// 设置编码，防止中文乱码
mysqli_query($conn , "set names utf8");

$sql = 'SELECT runoob_id, runoob_title,
 runoob_author, submission_date
 FROM runoob_tbl';

mysqli_select_db( $conn, 'RUNOOB' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
die('无法读取数据: ' . mysqli_error($conn));
}
echo '<h2>菜鸟教程 mysqli_fetch_array 测试<h2>';
echo '<table border="1"><tr><td>教程 ID</td><td>标题</td><td>作者</td><td>提交日期</td></tr>';
while($row = mysqli_fetch_array($retval, MYSQLI_NUM))
{
echo "<tr><td> {$row}</td> ".
 "<td>{$row} </td> ".
 "<td>{$row} </td> ".
 "<td>{$row} </td> ".
 "</tr>";
}
echo '</table>';
mysqli_close($conn);
?></pre>
</div>
<h2 class="example">使用 mysqli_free_result 释放内存：</h2>
<div class="cnblogs_code">
<pre><?php
$dbhost = 'localhost:3306';// mysql服务器主机地址
$dbuser = 'root'; // mysql用户名
$dbpass = '123456'; // mysql用户名密码
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
die('连接失败: ' . mysqli_error($conn));
}
// 设置编码，防止中文乱码
mysqli_query($conn , "set names utf8");

$sql = 'SELECT runoob_id, runoob_title,
 runoob_author, submission_date
 FROM runoob_tbl';

mysqli_select_db( $conn, 'RUNOOB' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
die('无法读取数据: ' . mysqli_error($conn));
}
echo '<h2>菜鸟教程 mysqli_fetch_array 测试<h2>';
echo '<table border="1"><tr><td>教程 ID</td><td>标题</td><td>作者</td><td>提交日期</td></tr>';
while($row = mysqli_fetch_array($retval, MYSQLI_NUM))
{
echo "<tr><td> {$row}</td> ".
 "<td>{$row} </td> ".
 "<td>{$row} </td> ".
 "<td>{$row} </td> ".
 "</tr>";
}
echo '</table>';
// 释放内存
mysqli_free_result($retval);
mysqli_close($conn);
?></pre>
</div>
  
来源：https://www.cnblogs.com/furuihua/p/11164368.html

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php MySQL 查询数据