Question

我正在构建一个项目，并希望从三个不同的表中检索数据，所以我正在使用INNER JOIN，但只是计算出它是重复数据，下面是它当前正在做的事情

Name: Ian Haney
First Line of Address: 12C Barclays Bank Chambers
Second Line of Address: Broadway North
Town: Pitsea
County: Essex
Postcode: SS13 3AU
Telephone Number: 01268 206297
Mobile Number: 07538 503276
Car Model: Jeep
Car Number Plate: AB10 1AB
Insurance expiry date: 30 July 2015
Name: Ian Haney
First Line of Address: 12C Barclays Bank Chambers
Second Line of Address: Broadway North
Town: Pitsea
County: Essex
Postcode: SS13 3AU
Telephone Number: 01268 206297
Mobile Number: 07538 503276
Car Model: Jeep
Car Number Plate: AB10 1AB
Tax expiry date: 30 June 2015

我想要的是以下

Name: Ian Haney
First Line of Address: 12C Barclays Bank Chambers
Second Line of Address: Broadway North
Town: Pitsea
County: Essex
Postcode: SS13 3AU
Telephone Number: 01268 206297
Mobile Number: 07538 503276
Car Model: Jeep
Car Number Plate: AB10 1AB
Tax expiry date: 30 June 2015
Insurance expiry date: 30 July 2015
MOT expiry date: 30 August 2015

有可能吗？

我的编码在

之下

<?php

if (logged_in() == false) {
    redirect_to("login.php");
} else {
    if (isset($_GET['id']) && $_GET['id'] != "") {
        $id = $_GET['id'];
    } else {
        $id = $_SESSION['user_id'];
    }

    ## connect mysql server
        $mysqli = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);
        # check connection
        if ($mysqli->connect_errno) {
            echo "<p>MySQL error no {$mysqli->connect_errno} : {$mysqli->connect_error}</p>";
            exit();
        }

    ## connect mysql server
        $mysqli = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);
        # check connection
        if ($mysqli->connect_errno) {
            echo "<p>MySQL error no {$mysqli->connect_errno} : {$mysqli->connect_error}</p>";
            exit();
        }
    ## query database
        # fetch data from mysql database

        $sql = "SELECT v.visitor_id, visitor_name, visitor_email, visitor_firstline, visitor_secondline, visitor_town, visitor_county, visitor_postcode, visitor_tel, visitor_mobile, visitor_model, visitor_plate, item.description, renewal_id, DATE_FORMAT(renewal_date, '%e %M %Y') as datedue, renewal_date FROM visitors v 
        INNER JOIN renewal USING (visitor_id)
        INNER JOIN item USING (item_id)
        WHERE renewal_date >NOW()";


        if ($result = $mysqli->query($sql)) {
            $user = $result->fetch_array();
            } else {
            echo "<p>MySQL error no {$mysqli->errno} : {$mysqli->error}</p>";
            exit();
            }

    if(mysqli_num_rows($result)) {  

   //fetch the data from the database 
while ($row = mysqli_fetch_array($result)) {

# echo the user profile data
            /*echo "<p>User ID: {$user['id']}</p>";*/
            echo "<p>Name: {$user['visitor_name']}</p>";
            echo "<p>First Line of Address: {$user['visitor_firstline']}</p>";
            echo "<p>Second Line of Address: {$user['visitor_secondline']}</p>";
            echo "<p>Town: {$user['visitor_town']}</p>";
            echo "<p>County: {$user['visitor_county']}</p>";
            echo "<p>Postcode: {$user['visitor_postcode']}</p>";
            echo "<p>Telephone Number: {$user['visitor_tel']}</p>";
            echo "<p>Mobile Number: {$user['visitor_mobile']}</p>";
            echo "<p>Car Model: {$user['visitor_model']}</p>";
            echo "<p>Car Number Plate: {$user['visitor_plate']}</p>";       
            echo "<p>" . $row['description'] . " expiry date: " . $row['datedue'] . "</p>\n";

}
        } else { // 0 = invalid user id
            echo "<p><b>Error:</b> Invalid user ID.</p>";
        }

}

?>

Answer 1

这需要工作：

SELECT v.visitor_id, visitor_name, visitor_email, visitor_firstline, visitor_secondline, visitor_town, visitor_county, visitor_postcode, visitor_tel, visitor_mobile, visitor_model, visitor_plate, item.description, renewal_id, DATE_FORMAT(renewal_date, '%e %M %Y') as datedue, renewal_date FROM visitors v 
            INNER JOIN renewal on (v.vistor_id = renewal.visitor_id)
            INNER JOIN item on (v.vistor_id = item.visitor_id)
            WHERE renewal_date >NOW()

链接3个表会导致你需要先扭曲2个表然后连接第3个表所需的性能不佳：

select a.* from (
SELECT v.visitor_id, visitor_name, visitor_email, visitor_firstline, visitor_secondline, visitor_town, visitor_county, visitor_postcode, visitor_tel, visitor_mobile, visitor_model, visitor_plate, item.description, renewal_id, DATE_FORMAT(renewal_date, '%e %M %Y') as datedue, renewal_date FROM visitors v 
        INNER JOIN renewal on (v.vistor_id = renewal.visitor_id) ) as a
        INNER JOIN item on (a.vistor_id = item.visitor_id)
        WHERE renewal_date >NOW()

Answer 2

啊，对不起，我有点困惑，所以它看起来像这样

$sql = "SELECT a.* from (
SELECT v.visitor_id, visitor_name, visitor_email, visitor_firstline, visitor_secondline, visitor_town, visitor_county, visitor_postcode, visitor_tel, visitor_mobile, visitor_model, visitor_plate, item.description, renewal_id, DATE_FORMAT(renewal_date, '%e %M %Y') as datedue, renewal_date FROM visitors v 
        INNER JOIN renewal on (v.vistor_id = renewal.visitor_id) ) as a
        INNER JOIN item on (a.vistor_id = item.visitor_id)
        WHERE renewal_date >NOW()";

使用INNER JOIN问题重复数据

2 个答案: