如何使用另一个表的ID显示一个表的属性

Question

I have the following tables in an Oracle database:

CREATE TABLE Team
 (
  teamID INT NOT NULL,
  teamName VARCHAR(50),
  wins INT,
  losses INT,
  otlosses INT,
  points INT,
  PRIMARY KEY (teamID)
);


    CREATE TABLE Matchup
       (
           matchID INT NOT NULL,
           roundID INT NOT NULL,
            team1ID INT NOT NULL,
            team2ID INT NOT NULL,
            PRIMARY KEY (matchID),
            FOREIGN KEY (roundID) REFERENCES Round (roundID),
            FOREIGN KEY (team1ID) REFERENCES Team (teamID),
            FOREIGN KEY (team2ID) REFERENCES Team (teamID) 
         );

I am looping through the matchup table and displaying all of the matchups. I can only get it to display the TeamID however and am trying to get it to display the teamName from the Team table using the IDs I am getting from the Matchup table.

this is what I am trying so far but can't seem to get it to work.

 $query = 'SELECT team1ID, team2ID  FROM Matchup WHERE RoundID=1 IN (SELECT teamName FROM Team WHERE team1ID=teamID AND team2ID=teamID)';

this is the rest of the php code which is supposed to display the information on my html page

 <h2>Round 1 Matchups</h2>
<table width=100%>
<tr>
    <th title="team1ID">Team</th>
    <th title="team2ID">Team</th>

</tr>

             <?php
           // Remember to replace 'username' and 'password'!
          $conn = oci_connect('xx', 'xxx', '(DESCRIPTION=(ADDRESS_LIST=
          (ADDRESS=(PROTOCOL=TCP)(Host=db2.ndsu.edu)(Port=1521)))
          (CONNECT_DATA=(SID=cs)))');


         //put your query here
        $query = 'SELECT team1ID, team2ID  FROM Matchup WHERE RoundID=1 IN 
        (SELECT teamName FROM Team WHERE team1ID=teamID AND 
         team2ID=teamID)';
        $stid = oci_parse($conn,$query);
        oci_execute($stid,OCI_DEFAULT);

        //iterate through each row
        while ($row = oci_fetch_array($stid,OCI_ASSOC)) 
        {
         echo '<tr>';
         foreach ($row as $item)
        {
          echo '<td>' . $item . '</td>';
         }
          echo '</tr>';

        echo '<br>';}
        echo '</table>';
        oci_free_statement($stid);
       oci_close($conn);
         ?>

Answer 1

You can join twice on the team table twice, once for each team:

SELECT t1.name, t2.name
FROM   match m
JOIN   team t1 ON t1.teamid = m.team1id
JOIN   team t2 ON t2.teamid = m.team2id
WHERE  roundid = 1