Yadda ake amfani da MySQL inda sanarwa? inda juzu'i mahara sharuddan syntax

MySQL databaseYadda ake amfani da bayanin inda bayanin? inda juzu'i mahara sharuddan syntax

MySQL INA magana

Mun san yin amfani da bayanin SQL SELECT don karanta bayanai daga tebur MySQL.

Don zaɓar bayanai ta hanyar sharadi daga tebur, ƙara magana INA zuwa bayanin SELECT.

nahawu

Mai zuwa shine jigon bayanin SQL SELECT don karanta bayanai daga teburin bayanai ta amfani da jumlar INA:

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

• Kuna iya amfani da tebur ɗaya ko fiye a cikin bayanin tambaya, ta amfani da waƙafi tsakanin teburi, Raba, kuma yi amfani da bayanin WHERE don saita sharuɗɗan tambaya.
• Kuna iya ƙayyade kowane yanayi a cikin jumlar INA.
• Kuna iya ƙayyade sharuɗɗa ɗaya ko fiye ta amfani da AND ko KO.
• Hakanan ana iya amfani da jumlar WHERE tare da SQL's DELETE ko UPDATE umarni.
• Sashe na WHERE yayi kama da idan yanayi a cikin yarukan tsari, kuma yana karanta ƙayyadaddun bayanai bisa ga ƙimar filin a cikin tebur MySQL.

Mai zuwa jerin masu aiki ne waɗanda za a iya amfani da su a cikin jumlar INA.

Misalai a cikin teburin da ke ƙasa suna ɗauka cewa A shine 10 kuma B shine 20

Maganar WHERE tana da amfani sosai idan muna son karanta ƙayyadaddun bayanai daga teburin bayanan MySQL.

Yin amfani da maɓalli na farko azaman tambayar sharadi a cikin INA magana yana da sauri.

Idan sharuɗɗan da aka bayar ba su da kowane bayanan da suka dace a cikin tebur, tambayar ba ta dawo da bayanai ba.

karanta bayanai daga umarni da sauri

Za mu yi amfani da jumlar WHERE a cikin bayanin SQL SELECT don karanta bayanai a cikin teburin bayanan MySQL chenweiliang_tbl:

misali

Misali mai zuwa zai karanta duk bayanan da ke cikin chenweiliang_tbl tebur inda darajar filin chenweiliang_author shine Sanjay:

Kwatancen igiya a cikin MySQL's WHERE magana ba ta da hankali.Kuna iya amfani da kalmar BINARY don tantance cewa kwatancen kirtani a cikin INA juzu'in yana da hankali.

Misali mai zuwa:

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)

amfani a cikin misali BINARYI keyword, yana da hankali, don haka chenweiliang_author='chenweiliang.com' Yanayin tambaya ba bayanai bane.

Karanta bayanai ta amfani da rubutun PHP

Kuna iya amfani da aikin PHP mysqli_query() da kuma umarnin SQL SELECT iri ɗaya tare da jumla WHERE don samun bayanan.

Ana amfani da wannan aikin don aiwatar da umarnin SQL sannan a fitar da duk bayanan da aka nema ta hanyar aikin PHP mysqli_fetch_array().

misali

Misali mai zuwa zai dawo daga tebur chenweiliang_tbl ta amfani da ƙimar filin chenweiliang_author kamar chenweiliang.com rikodin:

MySQL WHERE gwajin jumla:

<?
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);
?>