查询数据
语法:SELECT column_name,column_name FROM tabel_name;
- 一个或多个表(查询时)
- SELECTk而已读取一条躲着多条记录
- *代替其他字段,SELECT会返回表的所有字段数据
- WHERE语句来包含任何条件
- LIMIT属性来设定返回的记录数
- OFFSET指定SELECT语句开始查询的数据偏移量。默认情况下偏移量为0。
通过命令提示符获取数据
使用PHP脚本来获取数据
mysqli_fetch_array()
语法:myslqi_fetch_array(result,resulttype);
- result:规定由mysql_query(),mysql_store_result()或mysqli_use_result()返回的结果集标识符(必须)。
- resulttype: 规定应该产生那种类型的数组(可选)
MYSQLI_ASSOC:关联数组
MYSQLI_NUM:数字数组
MYSQLI_BOTH:都返回
<?php
header("content-type:text/html;charset=utf-8");
$dbhost='localhost';
$dbuser='root';
$dbpass='root';
$conn = mysqli_connect($dbhost,$dbuser,$dbpass);
if(!$conn)
{
die('连接失败:'.mysqli_error($conn));
}
mysqli_query($conn,"set names utf-8");
$sql='SELECT id,title,author,submission_date FROM bird_tbl';
mysqli_select_db($conn,'bird');
$retval=mysqli_query($conn,$sql);
if(!$retval)
{
die('无法读取数据:'.mysqli_error($conn));
}
echo '<h2>mysqli_fetch_array</h2>';
echo '<table border="1"> <tr><td>ID</td><td>标题</td><td>作者</td><td>时间</td></tr>';
while($row=mysqli_fetch_array($retval,MYSQLI_ASSOC))
{
echo "<tr><td>{$row['id']}</td>".
"<td>{$row['title']}</td>".
"<td>{$row['author']}</td>".
"<td>{$row['submission_date']}</td>".
"</tr>";
}
echo '</table>';
mysqli_close($conn);
?>
mysqli_fetch_assoc()
该函数从结果集中取得一行为关联数组。返回根据从结果集取得行生成的关联数组,若果没有更多行,则返回false.
<?php
header("content-type:text/html;charset=utf-8");
$dbhost='localhost';
$dbuser='root';
$dbpass='root';
$conn=mysqli_connect($dbhost,$dbuser,$dbpass);
if(!$conn)
{
die('连接失败:'.mysqli_error($conn));
}
mysqli_query($conn,"set names utf8");
$sql = 'SELECT id,title,author,submission_date FROM bird_tbl';
mysqli_select_db($conn,'bird');
$retval=mysqli_query($conn,$sql);
if(!$retval)
{
die('无法读取数据:'.mysqli_error($conn));
}
echo '<h2>mysqli_fetch_assoc</h2>';
echo '<table border="1"><tr><td>id</td><td>标题</td><td>作者</td><td>时间</td></tr>';
while($row=mysqli_fetch_assoc($retval))
{
echo "<tr><td>{$row['id']}</td>".
"<td>{$row['title']}</td>".
"<td>{$row['author']}</td>".
"<td>{$row['submission_date']}</td>".
"</tr>";
}
echo '</table>';
mysqli_close($conn);
?>
MYSQLI_NUM
<?php
header("content-type:text/html;charset=utf-8");
$dbhost='localhost';
$dbuser='root';
$dbpass='root';
$conn=mysqli_connect($dbhost,$dbuser,$dbpass);
if(!$conn)
{
die('连接失败:'.mysqli_error($conn));
}
mysqli_query($conn,"set names utf8");
$sql= 'SELECT id,title,author,submission_date FROM bird_tbl';
mysqli_select_db($conn,'bird');//使用数据库
$retval=mysqli_query($conn,$sql);
if(!$retval)
{
die('无法读取数据:'.mysqli_error($conn));
}
echo '<h2>MYSLQI_NUM</h2>';
echo '<table border="1"><tr><td>id</td><td>标题</td><td>作者</td><td>时间</td>';
while($row=mysqli_fetch_array($retval,MYSQLI_NUM))
{
echo "<tr><td>{$row[0]}</td>".
" <td>{$row[1]}</td>".
" <td>{$row[2]}</td>".
" <td>{$row[3]}</td>".
" </tr>";
}
echo '</table>';
mysqli_free_result($retval);//释放内存
mysqli_close($conn);
?>