PHP，MySQL-连接

Question

I am new to PHP and I just cannot figure out my code. I am using MySQL and PHP.

table: person PK: personID Other fields: lastName, firstName, hireDate, imgName

table: validMajors PK: majorAbbrev Other Fields: majorDesc

(Junction) table: personMajors personID, majorAbbrev

When I run my code (using NATURAL JOIN ) it will display the image, last&first name, and hire date. Which is great! But I need it to display their majors as well (I would like the majorAbbrev to be displayed). It also does not display people who are in the person table but are not in the personMajors table, which is an issue because we have staff members in the person table (who do not have a major since they are not a student)

Here is my code:

<table align="center">
    <?php
        $connection = mysqli_connect(DBHOST, DBUSER, DBPASS, DBNAME);

        if ( mysqli_connect_errno() ) {
           die( mysqli_connect_error() );  
        }
        $sql = "SELECT * FROM person NATURAL JOIN personMajors ORDER BY lastName";

        if ($result = mysqli_query($connection, $sql)) {     
           // loop through the data

           $columns=4;
           $i = 0;
            while($row = mysqli_fetch_assoc($result))
            {

            if($i % $columns ==0){


                 echo "<tr>";
                 }

                 echo "<td class='staffImage badgeText frameImage displayInLine'>" . "<img src='images/staff/".$row['imgName'].".jpg'>". "<br>". 
                                                            "<strong>" . $row['firstName'] . "</strong>" ." ". 
                                                            "<strong>" . $row['lastName'] . "</strong>" . "<br>" .
                                                            "Hire Date: ".$row['hireDate'] ."</td>";
                                                            "Major: " .$row['majorAbbrev'] ."</td>";     //Does not display

if($i % $columns == ($columns - 1)){
                 echo "</tr>";               
            }

            $i++;
            }
            // release the memory used by the result set
            mysqli_free_result($result); 
        } 
        // close the database connection
        mysqli_close($connection); 
    ?>
    </table>

Any ideas/solution will be greatly appreciated!

Answer 1

Because you are not concatenating your php properly. You ended ( ; ) your echo after displaying the $row["lastName"] .

You can try these to join the three tables:

SELECT * FROM person
       LEFT JOIN personMajors ON person.personID = personMajors.personID
       LEFT JOIN validMajors ON personMajors.majorAbbrev = validMajors.majorAbbrev

Or you can define what columns to call in your query:

SELECT person.personID,
       person.lastName,
       person.firstName,
       person.hireDate,
       person.imgName,
       validMajors.majorAbbrev,
       validMajors.majorDesc
FROM person
       LEFT JOIN personMajors ON person.personID = personMajors.personID
       LEFT JOIN validMajors ON personMajors.majorAbbrev = validMajors.majorAbbrev

Then you can call the results with the way you are calling it right now (cleaner version):

echo '<td class="staffImage badgeText frameImage displayInLine">
          <img src="images/staff/'.$row["imgName"].'.jpg"><br>
          <strong>'.$row["firstName"].'</strong>
          <strong>'.$row["lastName"].'</strong><br>
          Hire Date: '.$row["hireDate"].'
          Major: '.$row["majorAbbrev"].'
      </td>';

Answer 2

(Second try): Is the person to major relationship one to one or one to many?

OK, this SELECT Statement should work:

SELECT person.*, validMajors.* FROM person AS p, validMajors AS vm,   personMajors AS pm WHERE p.personID = pm.personID AND pm.majorAbbrev = vm.majorAbbrev