Question

我是一名初学者，也是一名文凭学生...我使用localhost创建了数据库...我有查看我的数据库的问题...请帮助我...我希望你可以帮我一个完整的代码..这是错误......

Warning: mysqli_select_db() expects exactly 2 parameters, 1 given in C:\xampp\htdocs\SLR\View S110 PC01.php on line 10
cannot select DB

这是我的代码......

<?php
$host="localhost"; // Host name 
$username="root"; // Mysql username 
$password=""; // Mysql password 
$db_name="slr"; // Database name 
$tbl_name="s110_pc01"; // Table name 

// Connect to server and select databse.
mysqli_connect("$host", "$username", "$password")or die("cannot connect"); 
mysqli_select_db("$db_name")or die("cannot select DB");

$sql="SELECT * FROM $tbl_name";
$result=mysqli_query($sql);

$count=mysqli_num_rows($result);
?>

<table width="400" border="0" cellspacing="1" cellpadding="0">
<tr>
<td><form name="form1" method="post" action="">
<table width="400" border="0" cellpadding="3" cellspacing="1" bgcolor="#CCCCCC">
<tr>
<td bgcolor="#FFFFFF">&nbsp;</td>
<td colspan="4" bgcolor="#FFFFFF"><strong>Delete multiple rows in mysql</strong> </td>
</tr>
<tr>
<td align="center" bgcolor="#FFFFFF">#</td>
<td align="center" bgcolor="#FFFFFF"><strong>Software ID</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Software Name</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Installed Date</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Expiry Date</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Product Key</strong></td>
</tr>

<?php
while($rows=mysqli_fetch_array($result)){
?>

<tr>
<td align="center" bgcolor="#FFFFFF"><input name="checkbox[]" type="checkbox" id="checkbox[]" value="<? echo $rows['id']; ?>"></td>
<td bgcolor="#FFFFFF"><? echo $rows['soft_id']; ?></td>
<td bgcolor="#FFFFFF"><? echo $rows['soft_name']; ?></td>
<td bgcolor="#FFFFFF"><? echo $rows['installed_date']; ?></td>
<td bgcolor="#FFFFFF"><? echo $rows['expiry_date']; ?></td>
<td bgcolor="#FFFFFF"><? echo $rows['product_key']; ?></td>
</tr>

<?php
}
?>

<tr>
<td colspan="5" align="center" bgcolor="#FFFFFF"><input name="delete" type="submit" id="delete" value="Delete"></td>
</tr>

<?php

// Check if delete button active, start this 
if($delete){
for($i=0;$i<$count;$i++){
$del_id = $checkbox[$i];
$sql = "DELETE FROM $tbl_name WHERE soft_id='$soft_id'";
$result = mysqli_query($sql);
}
// if successful redirect to delete_multiple.php 
if($result){
echo "<meta http-equiv=\"refresh\" content=\"0;URL=View S110 PC01.php\">";
}
}
mysqli_close();
?>

</table>
</form>
</td>
</tr>
</table>

Answer 1

如果你在这里查看php手册：http://php.net/manual/fr/mysqli.select-db.php

你会看到函数mysqli_select_db输入两个参数。

bool mysqli_select_db（mysqli $ link，string $ dbname）

所以你应该

// Connect to server and select databse.
$conn = mysqli_connect($host, $username, $password) or die("cannot connect"); 
mysqli_select_db($conn, $db_name) or die("cannot select DB");

Answer 2

你不需要在mysqli函数中选择数据库的单独函数，

以下方法足以连接和选择数据库，

 // Connect to server and select databse.
    $conn = mysqli_connect($host, $username, $password,$db_name)or die("cannot connect");

doc：http://php.net/manual/en/mysqli.select-db.php

Answer 3

$known_teams = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

$query = "SELECT winning_team, group_concat(losing_team) AS losing_team_str FROM history GROUP BY winning_team";
$result = mysqli_query($db, $query);

while ($row = $result->fetch_object()) {
    $loosing_teams = explode(",", $row->losing_team_str)
    $not_played_teams = array_diff($known_teams, $loosing_teams);

    echo "Team ". $row->winning_team ." \n";
    echo "hasn't played with teams: " . implode(", ", $not_played_teams) ."<br />\n";
}

警告：mysqli_select_db（）正好需要2个参数，给出1

3 个答案: