Sida loo isticmaalo MySQL halkee bayaanada? halkaas oo faqrad shuruudo badan leh

database MySQLSida loo isticmaalo bayaan halkee ah? halkaas oo faqrad shuruudo badan leh

MySQL HALKEE qodob

Waxaan ognahay inaan isticmaalno bayaanka SQL SELECT si aan ugu akhrino xogta miiska MySQL.

Si aad shuruud ahaan xogta uga xusho miis, ku dar qodob HALKEE ku jira bayaanka SELECT.

naxwaha

Kuwa soo socdaa waa jumlada guud ee bayaanka SQL SELECT si loo akhriyo xogta shaxda xogta iyadoo la adeegsanayo qodobka HALKEE:

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

• Waxaad isticmaali kartaa hal ama in ka badan oo jadwal ah oo ku jira bayaanka weydiinta, adoo isticmaalaya joosyada u dhexeeya miisaska, Kala qaybso, oo isticmaal bayaanka WHERE si aad u dejiso shuruudaha weydiinta.
• Waxaad ku qeexi kartaa xaalad kasta oo ku jirta qodobka HALKEE.
• Waxaad cayimi kartaa hal ama in ka badan oo shuruudo ah addoo isticmaalaya AND ama AMA
• Qoddobka WHERE waxa kale oo lagu isticmaali karaa SQL's DELETE ama UPDATE.
• Qodobka HALKEE wuxuu la mid yahay haddii xaalad ku jirta luqadda barnaamijka, akhrinta xogta la cayimay iyadoo loo eegayo qiimaha goobta ee miiska MySQL.

Kuwa soo socda waa liiska hawl-wadeenada loo isticmaali karo faqradda HALKEE.

Tusaalooyinka shaxda hoose waxay u qaadanayaan in A uu yahay 10 halka B uu yahay 20

Qodobka WHERE aad buu faa'iido u leeyahay haddii aan rabno inaan akhrino xogta la cayimay ee miiska xogta MySQL.

Isticmaalka furaha aasaasiga ah sidii su'aal shuruudaysan oo ku jirta halkee qodobku aad u degdeg badan yahay.

Haddii shuruudaha la bixiyay aysan ku lahayn wax diiwaanno ah oo u dhigma shaxda, weydiintu wax xog ah kama soo celinayso.

akhri xogta degdega ah

Waxaan u isticmaali doonaa qodobka WHERE ee bayaanka SQL SELECT si aan u akhrino xogta ku jirta miiska xogta MySQL chenweiliang_tbl:

tusaale

Tusaalaha soo socda ayaa akhrin doona dhammaan diiwaanada ku jira miiska chenweiliang_tbl halkaas oo qiimaha chenweiliang_author goobta uu yahay Sanjay:

Isbarbardhigga xargaha ee MySQL's WHERE faqradu waa arrin aan dareen lahayn.Waxaad isticmaali kartaa erayga muhiimka ah ee 'BINARY' si aad u qeexdo isbarbardhigga xargaha ee ku jira WHERE clause waa kiis xasaasi ah.

Tusaalaha soo socda:

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)

loo isticmaalo tusaale ahaan Aasaaska keyword, waa kiis xasaasi ah, sidaas darteed chenweiliang_author='chenweiliang.com' Xaaladda weydiintu ma aha xog.

Akhri xogta adoo isticmaalaya qoraalka PHP

Waxaad isticmaali kartaa PHP function mysqli_query() iyo isla amarka SQL SELECT oo leh jeex jeex ah si aad xogta u hesho.

Shaqadan waxaa loo isticmaalaa in lagu fuliyo amarrada SQL ka dibna lagu soo saaro dhammaan xogta la waydiiyay iyada oo loo marayo PHP function mysqli_fetch_array().

tusaale

Tusaalaha soo socda ayaa ka soo laaban doona miiska chenweiliang_tbl iyadoo la isticmaalayo chenweiliang_author qiimaha goobta sida chenweiliang.com diiwaanka:

MySQL WHERE imtixaanka qodobka:

<?
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);
?>