从mysql表

Question

我有一个小脚本，从2个单独的表中加入2行并将它们一起打印。

但是，我想从2个单独的表中逐个拉出并打印这2个分开的行（分别为css设计每一行结果）而不是JOIN

sql JOIN进程：

SELECT  b.topic, a.message,  a.threadID 
FROM wbb1_post a
JOIN wbb1_thread b ON b.threadID = a.threadID

整个脚本 index3.php ：

<?php
//header('Content-Type: text/html; charset=utf-8');
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "dbname";
$id =(int)$_GET['id'];
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 
mysqli_set_charset($conn,"utf8");


$sql = "SELECT  b.topic, a.message,  a.threadID 
FROM wbb1_post a
JOIN wbb1_thread b ON b.threadID = a.threadID 
 WHERE a.threadID = $id";
//print_r
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        $obj[] = $row;
    }
} else {

}
$conn->close();
?>

test1.php 页面代码：

<div>
<?php
$_GET['id'] = 4;
include 'index3.php'  ;?>
</div>

单独打印2行结果我想到了类似的东西：

index3.php 代码：

$sql = "SELECT  a.message,  a.threadID 
FROM wbb1_post a
 WHERE a.threadID = $id";

$sql2 = "SELECT  b.topic, b.threadID
FROM wbb1_thread b 
WHERE b.threadID = $sub";

//print_r
$result = $conn->query($sql);
$result = $conn->query($sql2);
if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        $obj[] = $row;
    }
} else {

}
$conn->close();
?>

test1.php 代码：

<div>
<?php
$_GET['sub'] = 4;
include 'index3.php'  ;?>
</div>
<br><br>
<div>
<?php
$_GET['id'] = 4;  
include 'index3.php' ;?>
</div>

但我得到的是主题行['id']两次。

Answer 1

使用UNION

$sql = "SELECT a.message AS Val,  a.threadID 
FROM wbb1_post a WHERE a.threadID = $id
UNION ALL 
SELECT b.topic AS Val,  b.threadID 
FROM wbb1_post a WHERE b.threadID = $id";