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

Ungabuza kanjani idatha etafuleni elisedathabheyisini ye-MySQL ? 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

Sebenzisa umsebenzi we-PHP i-mysqli_query() kanye nomyalo we-SQL SELECT ukuze uthole idatha.

Lo msebenzi usetshenziselwa ukwenza imiyalo ye-SQL, bese kuthi umsebenzi we-PHP i-mysqli_fetch_array() usetshenziswe ukufinyelela noma ukukhipha yonke idatha ebuziwe.

Umsebenzi we -mysqli_fetch_array() uthatha umugqa kusukela kusethi yemiphumela njenge-associative array, i-number array, noma kokubili, bese ubuyisela i-array ekhiqizwe kusukela kumugqa othathwe kusethi yemiphumela. Uma kungekho eminye imigqa, ibuyisa amanga.

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 ukufaka i-variable kuma-curly braces uma udinga ukuyisebenzisa ku-string.

Esibonelweni esingenhla, ipharamitha yesibili yomsebenzi we-PHP mysqli_fetch_array() yi -MYSQL_ASSOC . Ukusetha le pharamitha kubuyisela i-associative array, futhi ungasebenzisa igama lensimu njengenkomba ye-array.

I-PHP inikeza omunye umsebenzi, `mysqli_fetch_assoc()` , othola umugqa owodwa kusuka kusethi yemiphumela njenge-associative array. Ibuyisa i-associative array ngokusekelwe kumigqa ethathwe kusethi yemiphumela; uma kungekho eminye imigqa etholakalayo, ibuyisa amanga.

Isibonelo

Zama isibonelo esilandelayo, esisebenzisa umsebenzi we- mysqli_fetch_assoc() ukukhipha wonke amarekhodi ethebula le-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

Isibonelo esilandelayo sisebenzisa ipharamitha ye-MYSQL_NUM ukubonisa wonke amarekhodi etafuleni elithi 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);
?>