Ngabe idatha yedatha yedatha ye-MySQL iyibuza kanjani etafuleni?Isitatimende Sombuzo/Umyalo/Isintaksi

MySQL databaseUngabuza kanjani idatha esethebulani?Isitatimende Sombuzo/Umyalo/Isintaksi

MySQL Idatha yombuzo

Imininingo egciniwe ye-MySQL isebenzisa izitatimende ze-SQL KHETHA ukubuza ngedatha.

Ungakwazi ukubuza idatha ku-database ngokusebenzisa mysql> iwindi lomyalo womyalo, noma ngombhalo we-PHP.

uhlelo lolimi

Okulandelayo i-syntax evamile ethi KHETHA yokubuza idatha kusizindalwazi se-MySQL:

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

• Esitatimendeni sombuzo, ungasebenzisa ithebula elilodwa noma amaningi, uhlukanise amathebula ngokhefana (,), futhi usebenzise isitatimende esithi WHERE ukuze usethe izimo zombuzo.
• Umyalo othi KHETHA ungafunda irekhodi elilodwa noma amaningi.
• Ungasebenzisa inkanyezi (*) ukuze umiselele ezinye izinkambu, isitatimende esithi KHETHA sizobuyisela yonke idatha yethebula.
• Ungasebenzisa isitatimende esithi LAPHO ukufaka noma yisiphi isimo.
• Ungacacisa i-offset yedatha lapho isitatimende esithi KHETHA siqala khona umbuzo ngokuthi OFFSET.Ngokuzenzakalelayo i-offset ingu-0.
• Ungasebenzisa isakhiwo esingu-LIMIT ukuze usethe inombolo yamarekhodi abuyisiwe.

Thola idatha ngokusebenzisa umyalo womyalo

Esibonelweni esilandelayo, sizosebenzisa umyalo we-SQL KHETHA ukuze sithole idatha yethebula ledatha le-MySQL chenweiliang_tbl:

Isibonelo

Isibonelo esilandelayo sizobuyisela wonke amarekhodi ethebula ledatha chenweiliang_tbl:

select * from chenweiliang_tbl;

Sebenzisa umbhalo we-PHP ukuze uthole idatha

usebenzisa imisebenzi ye-PHP mysqli_query() futhi SQL KHETHA umyalo wokuthola idatha.

Lo msebenzi usetshenziselwa ukwenza imiyalo ye-SQL bese udlula imisebenzi ye-PHP mysqli_fetch_array() ukusebenzisa noma ukukhipha idatha yayo yonke imibuzo.

mysqli_fetch_array() Umsebenzi ulanda umugqa kumphumela omisiwe njengohlelo oluhlangene, noma izinombolo zezinombolo, noma kokubili. Ibuyisela amalungu afanayo akhiqizwe emigqeni elandiwe kusethi yomphumela, noma amanga uma ingasekho imigqa.

Isibonelo esilandelayo sifunda wonke amarekhodi kuthebula ledatha elithi chenweiliang_tbl.

Isibonelo

Zama isibonelo esilandelayo ukuze ubonise wonke amarekhodi ethebula ledatha 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);
?>

Esibonelweni esingenhla, umugqa ngamunye wamarekhodi afundiwe ubelwa kumugqa we-$ oguquguqukayo, bese inani ngalinye liphrintiwe.

Qaphela:Khumbula ukuthi uma udinga ukusebenzisa okuguquguqukayo entanjeni, faka okuguquguqukayo kumabrace asontekile.

Kulesi sibonelo esingenhla, ipharamitha yesibili yomsebenzi we-PHP mysqli_fetch_array() ithi I-MYSQL_ASSOC, setha le pharamitha ukuze ubuze umphumela ukuze ubuyisele amalungu afanayo, ungasebenzisa igama lenkambu njengenkomba yamalungu afanayo.

I-PHP inikeza omunye umsebenzi mysqli_fetch_assoc(), umsebenzi uthatha umugqa kusukela kumphumela omisiwe njengamalungu afanayo.Ibuyisela iqembu elihlangene elikhiqizwe emigqeni ethathwe kusethi yomphumela, noma amanga uma ingasekho imigqa.

Isibonelo

Zama isibonelo esilandelayo, esisebenzisayo mysqli_fetch_assoc() umsebenzi wokukhipha wonke amarekhodi wethebula ledatha 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);
?>

Ungasebenzisa futhi i-MYSQL_NUM engaguquki njengepharamitha yesibili yomsebenzi we-PHP mysqli_fetch_array(), obuyisela izinombolo eziningi.

Isibonelo

Izibonelo ezilandelayo zisetshenziswa MYSQL_NUM Ipharamitha ibonisa wonke amarekhodi ethebula ledatha 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);
?>

ukukhululwa kwenkumbulo

Kuwumkhuba omuhle ukukhulula inkumbulo yesikhombisi ngemva kokwenza isitatimende esithi KHETHA.

Imemori ingakhululwa ngomsebenzi we-PHP mysqli_free_result().

Isibonelo esilandelayo sibonisa ukusetshenziswa kwalo msebenzi.

Isibonelo

Zama izibonelo ezilandelayo:

Inkumbulo yamahhala enomphumela we-mysqli_free_:

<?
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);
?>