mysql 处理 null值_MySQL NULL 值处理

$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($conn , "set names utf8");if( isset($runoob_count))

{$sql = "SELECT runoob_author, runoob_count

FROM runoob_test_tbl

WHERE runoob_count =$runoob_count";

}else{$sql = "SELECT runoob_author, runoob_count

FROM runoob_test_tbl

WHERE runoob_count IS NULL";

}mysqli_select_db( $conn, ‘RUNOOB‘);$retval = mysqli_query( $conn, $sql);if(! $retval)

{die(‘无法读取数据: ‘ . mysqli_error($conn));

}echo ‘

菜鸟教程 IS NULL 测试

‘;echo ‘

{echo "

"

"

"

}echo ‘

MySQL NULL 值处理

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本文系统来源：https://www.cnblogs.com/furuihua/p/11176985.html