Uyisebenzisa njani iMySQL apho ingxelo? apho igatya lemiqathango emininzi isivakalisi

MySQL databaseIndlela yokusebenzisa apho ingxelo? apho igatya lesivakalisi esinemiqathango emininzi

MySQL PHI igatya

Siyazi ukusebenzisa ingxelo ye-SQL KHETHA ukufunda idatha kwitafile ye-MySQL.

Ukukhetha idatha kwitheyibhile ngokwemeko, yongeza igatya apho u-KHETHA.

Igrama

Oku kulandelayo sisintaksi ngokubanzi yengxelo ye-SQL KHETHA ukufunda idatha kwitafile yedatha usebenzisa igatya elithi WHERE:

SELECT field1, field2,...fieldN FROM table_name1, table_name2...
[WHERE condition1 [AND [OR]] condition2.....

• Ungasebenzisa itafile enye okanye ngaphezulu kwingxelo yombuzo, usebenzisa iikoma phakathi kweetafile, Yahlula, kwaye usebenzise i-WHERE ingxelo ukuseta iimeko zombuzo.
• Ungakhankanya nayiphi na imeko kwigatya apho.
• Ungakhankanya imiqathango enye okanye ngaphezulu usebenzisa KUNYE okanye OKANYE.
• Igatya apho igatya linokusetyenziswa ne-SQL's DELETE okanye HLAZIYA imiyalelo.
• Igatya elithi WHERE lifana ne-if imeko kwiilwimi zenkqubo, kwaye ifunda idatha ekhankanyiweyo ngokwexabiso lendawo kwitheyibhile yeMySQL.

Oku kulandelayo luludwe lwabasebenzisi abanokusetyenziswa kwigatya elithi APHO.

Imizekelo ekwitheyibhile engezantsi ithatha ukuba uA ngu-10 kunye no-B ngama-20

Igatya elithi WHERE liluncedo kakhulu ukuba sifuna ukufunda idatha ekhankanyiweyo kwitafile yedatha yeMySQL.

Ukusebenzisa isitshixo esingundoqo njengombuzo onemiqathango kwigatya APHO kukhawuleza kakhulu.

Ukuba imilinganiselo enikiweyo ayinazo iirekhodi ezihambelanayo kwitheyibhile, umbuzo awubuyisi idatha.

funda idatha kwi-prompt yomyalelo

Siza kusebenzisa igatya elithi WHERE kwingxelo ye-SQL KHETHA ukufunda idatha kwitafile yedatha ye-MySQL chenweiliang_tbl:

Umzekelo

Lo mzekelo ulandelayo uyakufunda zonke iirekhodi kwitheyibhile ye-chenweiliang_tbl apho ixabiso le-chenweiliang_indawo yombhali nguSanjay:

Uthelekiso lomtya kwi-MySQL's APHO igatya alinaluvelwano.Ungasebenzisa i-BINARY igama elingundoqo ukucacisa ukuba uthelekiso lomtya kwi-APHO igatya lunobuzaza.

Lo mzekelo ulandelayo:

mysql> SELECT * from chenweiliang_tbl WHERE BINARY chenweiliang_author='chenweiliang.com';
Empty set (0.01 sec)
 
mysql> SELECT * from chenweiliang_tbl WHERE BINARY chenweiliang_author='chenweiliang.com';
+-----------+---------------+---------------+-----------------+
| chenweiliang_id | chenweiliang_title | chenweiliang_author | submission_date |
+-----------+---------------+---------------+-----------------+
| 3 | JAVA 教程 | chenweiliang.com | 2016-05-06 |
| 4 | 学习 Python | chenweiliang.com | 2016-03-06 |
+-----------+---------------+---------------+-----------------+
2 rows in set (0.01 sec)

isetyenziswe kumzekelo IINKCUKACHA igama elingundoqo, linobuzaza, ngoko chenweiliang_author='chenweiliang.com' Umqathango wombuzo akukho datha.

Funda data usebenzisa PHP script

Ungasebenzisa umsebenzi we-PHP mysqli_query () kunye nomyalelo ofanayo SQL KHETHA kunye negatya APHO ukufumana idatha.

Lo msebenzi usetyenziselwa ukuphumeza imiyalelo yeSQL kwaye emva koko ukhuphe yonke idata ebuzwayo ngomsebenzi wePHP mysqli_fetch_array().

Umzekelo

Lo mzekelo ulandelayo uzakubuya kwitheyibhile ye chenweiliang_tbl usebenzisa ixabiso lendawo ye chenweiliang_author njenge chenweiliang.com irekhodi ye:

MySQL APHO uvavanyo lwegatya:

<?
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");
 
// 读取 chenweiliang_author 为 chenweiliang.com 的数据
$sql = 'SELECT chenweiliang_id, chenweiliang_title, 
 chenweiliang_author, submission_date
 FROM chenweiliang_tbl
 WHERE chenweiliang_author="chenweiliang.com"';
 
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 MySQL WHERE 子句测试<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>';
// 释放内存
mysqli_free_result($retval);
mysqli_close($conn);
?>