Question

$sql_query_posts = "SELECT * FROM `posts`";

$sql_form_permission = mysql_query("SELECT * FROM `integrations` WHERE `rank_id`='$user_level' AND `mode`='form_per'");
    if ( mysql_num_rows($sql_form_permissions) > 0 ) {

现在我正在努力的部分：

   $sql_query_posts .= " IN (";
    while ( $row_form_permissions = mysql_fetch_assoc($sql_form_permissions) ) { 
    $sql_query_posts .= $row_form_permissions['form_id'] . ",";
    }
    $sql_query_posts .= ")";
    }

我希望输出类似于：

SELECT * FROM `posts` IN (4, 3, 2)

但上面的代码给出了如下输出：

SELECT * FROM `posts` IN (4, 3, 2,)

所以我必须在最后摆脱逗号。如何确保脚本禁用最后一行的逗号。

Answer 1

我会使用implode：

$post_ids = array();
while ( $row_form_permissions = mysql_fetch_assoc($sql_form_permissions) ) { 
    $post_ids[] = $row_form_permissions['form_id'];
}

$sql_query_posts .= " IN (" . implode(",", $post_ids) . ")";

Answer 2

像这样使用$sql_query_posts = substr($sql_query_posts, 0, -1);：

$sql_query_posts .= " IN (";
while ( $row_form_permissions = mysql_fetch_assoc($sql_form_permissions) ) { 
    $sql_query_posts .= $row_form_permissions['form_id'] . ",";
}
$sql_query_posts = substr($sql_query_posts, 0, -1);
$sql_query_posts .= ")";

只是为了解决你最终没有获取记录（一个空数组）的情况，使用implode（）可能更明智，就像这样（我总是这样使用它）：

$ins = array();
while ( $row_form_permissions = mysql_fetch_assoc($sql_form_permissions) ) {
    $ins[] = $row_form_permissions['form_id'];
}
$sql_query_posts .= sprintf(' IN (%s)', implode(',', $ins));

Answer 3

在我看来，比建议更漂亮的方式是：

$forms = array();
while ( $row_form_permissions = mysql_fetch_assoc($sql_form_permissions) )
  $forms[] = $row_form_permissions['form_id'];

$sql_query_posts .= " IN (".implode(",",$forms).")";

Answer 4

您可以使用substr关闭逗号。像这样：

$sql_query_posts .= " IN (";
while ( $row_form_permissions = mysql_fetch_assoc($sql_form_permissions) ) { 
$sql_query_posts .= $row_form_permissions['form_id'] . ",";
}
$sql_query_posts = substr($sql_query_posts, 0, -1); // <- this is the new line
$sql_query_posts .= ")";
}

Answer 5

作为substr的替代，您还可以使用trim删除逗号。

$sql_query_posts = trim($sql_query_posts, ',') . ')';

修剪比substr更安全，因为你可以将它限制为一个确切的字符或一组字符。

Answer 6

我会使用trim或（rtrim）函数就是这种情况（http://php.net/manual/en/function.trim.php）你给它一个字符串，并使用它的第二个参数指定额外的字符，并为你清理它。

逗号在MySQL查询中

6 个答案: