Kedu otu MySQL nchekwa data si ajụ data na tebụl?Nkwupụta ajụjụ/iwu/Syntax

MySQL nchekwa dataKedu otu esi ajụ ajụjụ data na tebụl?Nkwupụta ajụjụ/iwu/Syntax

MySQL Data ajụjụ

MySQL ọdụ data na-eji SQL SELECT nkwupụta iji jụọ data.

Ị nwere ike ịjụ data na nchekwa data site na mysql> windo ngwa ngwa, ma ọ bụ site na ederede PHP.

ụtọ asụsụ

Ihe a bụ mkpokọta SELECT syntax maka ajụjụ data na nchekwa data MySQL:

SELECT column_name,column_name
FROM table_name
[WHERE Clause]
[OFFSET M ][LIMIT N]

• Na nkwupụta ajụjụ, ị nwere ike iji otu tebụl ma ọ bụ karịa, kewaa tebụl na rịkọm (,), ma jiri nkwupụta WHERE tọọ ọnọdụ ajụjụ.
• Iwu SELECT nwere ike ịgụ otu ndekọ ma ọ bụ karịa.
• Ị nwere ike iji akara mmuke (*) dochie mpaghara ndị ọzọ, nkwupụta SELECT ga-eweghachite data ubi niile nke tebụl.
• Ị nwere ike iji nkwupụta WHERE tinye ọnọdụ ọ bụla.
• Ị nwere ike kọwapụta nkwụsị data nke nkwupụta SELECT na-amalite ajụjụ ahụ na OFFSET.Na ndabara, nkwụghachi bụ 0.
• Ị nwere ike iji ụlọ LIMIT ịtọ ọnụọgụ ndekọ eweghachiri.

Nweta data site na ngwa ngwa

N'atụmatụ na-esote, anyị ga-eji iwu SQL SELECT iji nweta data nke tebụl data MySQL chenweiliang_tbl:

ihe atụ

Ihe atụ na-esonụ ga-eweghachite ndekọ niile nke tebụl data chenweiliang_tbl:

select * from chenweiliang_tbl;

Jiri edemede PHP nweta data

iji PHP ọrụ mysqli_query() na Nhọrọ SQL iwu iji nweta data.

A na-eji ọrụ a mebie iwu SQL wee gafee ọrụ PHP mysqli_fetch_array() iji ma ọ bụ wepụta data maka ajụjụ niile.

mysqli_fetch_array() Ọrụ ahụ na-ewepụta ahịrị site na nsonaazụ atọrọ dị ka nhazi njikọ, ma ọ bụ n'usoro ọnụọgụgụ, ma ọ bụ ha abụọ. Na-eweghachi usoro ewepụtara site na ahịrị ndị ewepụtara na nsonaazụ ahụ, ma ọ bụ ụgha ma ọ bụrụ na enweghị ahịrị ọzọ.

Ihe atụ na-esonụ na-agụ ndekọ niile sitere na tebụl data chenweiliang_tbl.

ihe atụ

Gbalịa ihe atụ na-esonụ iji gosipụta ndekọ niile nke tebụl data chenweiliang_tbl.

<?
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 chenweiliang_id, chenweiliang_title, 
 chenweiliang_author, submission_date
 FROM chenweiliang_tbl';
 
mysqli_select_db( $conn, 'chenweiliang' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
 die('无法读取数据: ' . mysqli_error($conn));
}
echo '<h2>陈沩亮博客 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, MYSQL_ASSOC))
{
 echo "<tr><td> {$row['chenweiliang_id']}</td> ".
 "<td>{$row['chenweiliang_title']} </td> ".
 "<td>{$row['chenweiliang_author']} </td> ".
 "<td>{$row['submission_date']} </td> ".
 "</tr>";
}
echo '</table>';
mysqli_close($conn);
?>

N'ihe atụ dị n'elu, a na-ekenye ahịrị ndekọ ndekọ ọ bụla na mgbanwe $ ahịrị, wee bipụta uru ọ bụla.

Mara:Cheta na ọ bụrụ na ịchọrọ iji ihe agbanwe agbanwe na eriri, tinye mgbanwe ahụ n'ime ihe nkwado.

N'ihe atụ dị n'elu, paramita nke abụọ nke ọrụ PHP mysqli_fetch_array() bụ MYSQL_ASSOC, Tọọ oke a ka ị jụọ nsonaazụ iji weghachi otu ihe mmekọ, ị nwere ike iji aha mpaghara dị ka ndeksi nke nhazi ahụ.

PHP na-enye ọrụ ọzọ mysqli_fetch_assoc(), Ọrụ ahụ na-ewe ahịrị site na nsonaazụ atọrọ dị ka nhazi ihe mmekọ.Na-eweghachi usoro mmekọ emepụtara site na ahịrị ndị ewepụtara na nsonaazụ nchoputa, ma ọ bụ ụgha ma ọ bụrụ na enweghị ahịrị ọzọ.

ihe atụ

Gbalịa mee ihe atụ na-esonụ, nke na-eji mysqli_fetch_assoc() ọrụ iji wepụta ndekọ niile nke tebụl data chenweiliang_tbl:

<?
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 chenweiliang_id, chenweiliang_title, 
 chenweiliang_author, submission_date
 FROM chenweiliang_tbl';
 
mysqli_select_db( $conn, 'chenweiliang' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
 die('无法读取数据: ' . mysqli_error($conn));
}
echo '<h2>陈沩亮博客 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> {$row['chenweiliang_id']}</td> ".
 "<td>{$row['chenweiliang_title']} </td> ".
 "<td>{$row['chenweiliang_author']} </td> ".
 "<td>{$row['submission_date']} </td> ".
 "</tr>";
}
echo '</table>';
mysqli_close($conn);
?>

Ị nwekwara ike iji MYSQL_NUM mgbe niile dị ka paramita nke abụọ nke PHP mysqli_fetch_array() ọrụ, nke na-eweghachite ọtụtụ ọnụọgụgụ.

ihe atụ

Ihe atụ ndị a na-eji MYSQL_NUM Oke ihe ahụ na-egosiputa ndekọ niile nke tebụl data chenweiliang_tbl:

<?
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 chenweiliang_id, chenweiliang_title, 
 chenweiliang_author, submission_date
 FROM chenweiliang_tbl';
 
mysqli_select_db( $conn, 'chenweiliang' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
 die('无法读取数据: ' . mysqli_error($conn));
}
echo '<h2>陈沩亮博客 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, MYSQL_NUM))
{
 echo "<tr><td> {$row[0]}</td> ".
 "<td>{$row[1]} </td> ".
 "<td>{$row[2]} </td> ".
 "<td>{$row[3]} </td> ".
 "</tr>";
}
echo '</table>';
mysqli_close($conn);
?>

ntọhapụ ebe nchekwa

Ọ bụ omume dị mma ịtọhapụ ebe nchekwa cursor mgbe anyị mechara nkwupụta SELECT.

Enwere ike ịhapụ ebe nchekwa ahụ site na ọrụ PHP mysqli_free_result().

Ihe atụ na-esonụ na-egosi iji ọrụ a.

ihe atụ

Gbalịa ihe atụ ndị a:

Ebe nchekwa efu nwere mysqli_free_result:

<?
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 chenweiliang_id, chenweiliang_title, 
 chenweiliang_author, submission_date
 FROM chenweiliang_tbl';
 
mysqli_select_db( $conn, 'chenweiliang' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
 die('无法读取数据: ' . mysqli_error($conn));
}
echo '<h2>陈沩亮博客 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, MYSQL_NUM))
{
 echo "<tr><td> {$row[0]}</td> ".
 "<td>{$row[1]} </td> ".
 "<td>{$row[2]} </td> ".
 "<td>{$row[3]} </td> ".
 "</tr>";
}
echo '</table>';
// 释放内存
mysqli_free_result($retval);
mysqli_close($conn);
?>