Ta yaya MySQL database ke neman bayanan tambaya a cikin tebur?Bayanin Tambayoyi/Umurni/Syntax

MySQL databaseYadda ake tambayar bayanan da ke cikin tebur?Bayanin Tambayoyi/Umurni/Syntax

MySQL Bayanan tambaya

Bayanan bayanan MySQL suna amfani da bayanan SQL SELECT don neman bayanai.

Kuna iya neman bayanai a cikin bayanan ta hanyar mysql> umarni da sauri, ko ta hanyar rubutun PHP.

nahawu

Mai zuwa shine babban tsarin SELECT don neman bayanai a cikin bayanan MySQL:

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

• A cikin bayanin tambaya, zaku iya amfani da tebur ɗaya ko fiye, raba teburin tare da waƙafi (,), sannan yi amfani da bayanin INA don saita sharuɗɗan tambaya.
• Umurnin SELECT na iya karanta rikodin ɗaya ko fiye.
• Kuna iya amfani da alamar alama (*) don maye gurbin wasu filayen, bayanin SELECT zai dawo da duk bayanan filin tebur.
• Kuna iya amfani da bayanin WHERE don haɗa kowane sharadi.
• Kuna iya ƙididdige ɓarnar bayanan da bayanin SELECT ya fara tambayar tare da OFFSET.Ta hanyar tsohuwa abin biya shine 0.
• Kuna iya amfani da kayan LIMIT don saita adadin bayanan da aka dawo dasu.

Samo bayanai ta hanyar umarni da sauri

A cikin misali mai zuwa, za mu yi amfani da umarnin SQL SELECT don samun bayanan teburin bayanan MySQL chenweiliang_tbl:

misali

Misali mai zuwa zai dawo da duk bayanan teburin bayanai chenweiliang_tbl:

select * from chenweiliang_tbl;

Yi amfani da rubutun PHP don samun bayanai

ta amfani da ayyukan PHP mysqli_query() da SQL Zaɓi umarnin don samun bayanan.

Ana amfani da wannan aikin don aiwatar da umarnin SQL sannan a wuce ayyukan PHP mysqli_fetch_array() don amfani ko fitar da bayanai don duk tambayoyin.

mysqli_fetch_array() Aikin yana debo layi daga sakamakon da aka saita azaman haɗin haɗin gwiwa, ko jerin lambobi, ko duka biyu. Yana dawo da tsararrun da aka samo daga layuka da aka samo daga saitin sakamako, ko ƙarya idan babu sauran layuka.

Misali mai zuwa yana karanta duk bayanan daga teburin bayanai chenweiliang_tbl.

misali

Gwada wannan misali mai zuwa don nuna duk bayanan teburin bayanai 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);
?>

A cikin misalin da ke sama, kowane jeri na bayanan da aka karanta ana sanya shi zuwa madaidaicin $ jere, sa'an nan kuma ana buga kowace ƙima.

Lura:Ka tuna cewa idan kana buƙatar amfani da m a cikin kirtani, sanya m a cikin takalmin gyaran kafa.

A cikin misalin da ke sama, siga na biyu na aikin PHP mysqli_fetch_array() shine MYSQL_ASSOC, saita wannan siga don bincika sakamakon don dawo da tsararrun haɗin gwiwa, zaku iya amfani da sunan filin azaman fihirisar tsararrun.

PHP yana ba da wani aiki mysqli_fetch_assoc(), aikin yana ɗaukar jere daga sakamakon da aka saita azaman tsararrun haɗin gwiwa.Yana dawo da tsarin haɗin gwiwa da aka samar daga layuka da aka ɗauka daga saitin sakamako, ko ƙarya idan babu sauran layuka.

misali

Gwada misali mai zuwa, wanda ke amfani mysqli_fetch_assoc() aiki don fitar da duk bayanan teburin bayanai 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);
?>

Hakanan zaka iya amfani da MYSQL_NUM akai-akai azaman siga na biyu na aikin PHP mysqli_fetch_array(), wanda ke dawo da jeri na lambobi.

misali

Misalai masu zuwa suna amfani da su MYSQL_NUM Alamar tana nuna duk bayanan teburin bayanai 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);
?>

ƙwaƙwalwar ajiya

Yana da kyau al'ada don 'yantar da ƙwaƙwalwar siginan kwamfuta bayan mun aiwatar da bayanin SELECT.

Ana iya fitar da ƙwaƙwalwar ta hanyar aikin PHP mysqli_free_result().

Misali na gaba yana nuna amfanin wannan aikin.

misali

Gwada misalai masu zuwa:

Ƙwaƙwalwar ajiya kyauta tare da 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);
?>