Me pehea te whakamahi i te korero MySQL kei hea? kei reira te whiti wetereo herenga maha

pātengi raraunga MySQLMe pehea te whakamahi korero i hea? kei reira te whiti wetereo herenga maha

MySQL WHERE rara

E mohio ana matou ki te whakamahi i te korero SQL SELECT ki te panui raraunga mai i te ripanga MySQL.

Hei whiriwhiri i nga raraunga mai i te ripanga, taapirihia he rara WHERE ki te tauākī SELECT.

wetereo

E whai ake nei ko te wetereo whanui o tetahi tauākī SQL SELECT hei panui raraunga mai i te ripanga raraunga ma te whakamahi i te whiti WHERE:

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

• Ka taea e koe te whakamahi i tetahi ripanga, neke atu ranei i roto i te tauākī uiui, whakamahia nga piko i waenga i nga ripanga, Wehea, ka whakamahi i te tauākī WHERE hei whakatakoto tikanga uiui.
• Ka taea e koe te tohu i tetahi ahuatanga i roto i te rara WHERE.
• Ka taea e koe te whakamahi ME, OR ranei hei tohu i tetahi, neke atu ranei nga tikanga.
• Ka taea hoki te whakamahi te rara WHERE me nga whakahau a SQL's DELETE, UPDATE ranei.
• Ko te rara WHERE he rite ki te ahua mena kei roto i nga reo tikanga, ka panui i nga raraunga kua tohua kia rite ki te uara mara i te ripanga MySQL.

E whai ake nei he rarangi o nga kaiwhakahaere ka taea te whakamahi i roto i te rara WHERE.

Ko nga tauira o te ripanga i raro nei e kii ana he 10 a A ko te 20 a B

He tino whai hua te rara WHERE mena ka hiahia taatau ki te panui i nga raraunga kua tohua mai i te ripanga raraunga MySQL.

Ko te whakamahi i te matua matua hei uiui herenga i roto i te rara WHERE he tere rawa.

Mena karekau he rekoata rite ki nga paearu i te ripanga, karekau he raraunga e whakahokia e te uiui.

panui raraunga mai i te whakahau whakahau

Ka whakamahia e matou te whiti WHERE i roto i te korero SQL SELECT ki te panui i nga raraunga i te ripanga raraunga MySQL chenweiliang_tbl:

Akoranga

Ko te tauira e whai ake nei ka panui i nga rekoata katoa i te ripanga chenweiliang_tbl ko te uara o te mara chenweiliang_author ko Sanjay:

Ko nga whakataurite aho i roto i te rara WHERE a MySQL he take-kore.Ka taea e koe te whakamahi i te kupumatua BINARY ki te tohu he whakataurite aho i roto i te WHERE rara he take-tairongo.

Ko te tauira e whai ake nei:

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)

whakamahia i roto i te tauira Huarahi kupu matua, he take-tairongo, na chenweiliang_author='chenweiliang.com' Ko te tikanga patai he kore raraunga.

Pānuihia nga raraunga ma te whakamahi i te tuhinga PHP

Ka taea e koe te whakamahi i te mahi PHP mysqli_query() me taua whakahau SQL SELECT me te whiti WHERE hei tiki i nga raraunga.

Ka whakamahia tenei mahi ki te whakahaere i nga whakahau SQL ka whakaputa i nga raraunga patai katoa ma te mahi PHP mysqli_fetch_array().

Akoranga

Ko te tauira e whai ake nei ka hoki mai i te ripanga chenweiliang_tbl ma te whakamahi i te uara mara chenweiliang_author hei chenweiliang.com rekoata o:

MySQL WHERE rara whakamātautau:

<?
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);
?>