Question

我写了一个php文件来显示我数据库的最后一篇文章。我发现上一篇文章，但最后一篇文章没有标题我想要显示最后一篇文章和ech帖子没有标题副本从帖子有标题和相同的contentid.my数据库是大。我准备了一张pic，这是我的数据库的例子

这是我的php代码：

<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "vbtest";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 

$sql = "SELECT title , nodeid FROM node where contenttypeid='30' order by nodeid desc limit 10";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        echo "title: " . $row["nodeid"]. " title: " . $row["title"]. "<br>";
    }
} else {
    echo "0 results";
}
$conn->close();
?>

有人可以帮助我吗？

Answer 1

我认为子查询将有助于归档您的目标。在下面的SQL查询中，子查询将从外部查询中找到contentid的第一个标题。

$sql = "
SELECT 
       (SELECT N2.title FROM node AS N2
        WHERE N2.contentid = N.contentid
                  AND N2.starter = N.starter
        ORDER BY N2.nodeid ASC
        LIMIT 1) AS title,
        N.nodeid
FROM node AS N
WHERE contentid='30' 
ORDER BY nodeid DESC LIMIT 10";

Answer 2

那么，如何只留下一个唯一的标题和第一个带有排序的nodeid。

SELECT * FROM
(SELECT T.title,
       MIN(nodeid) AS nodeid
FROM
    (SELECT
           (SELECT N2.title FROM node AS N2
            WHERE N2.contentid = N.contentid
                  AND N2.starter = N.starter
            ORDER BY N2.nodeid ASC
            LIMIT 1) AS title,
            nodeid
    FROM node AS N
    WHERE contentid='30' 
    ORDER BY nodeid DESC LIMIT 10) AS T
GROUP BY title 
) AS T2
ORDER BY nodeid DESC

其中nodeid是最新的，如果不是具有相同内容id的nodeid的标题副本

2 个答案: