顯示多個表的結果 SQL/PHP

Question

我目前有一個包含 12 個表的數據庫。 我正在執行 php 查詢以從數據庫中提取信息，但沒有顯示任何內容。 單獨的查詢橋接了所有以表schedule開頭的表，這些表具有相關的外鍵。 我是否需要從表class開始查詢並與其他表橋接？

桌子設計-圖片

如果你想復制我的設計 - QUERY

$query = ("SELECT  class_name, class_caption, class_credit_hours, class_description
                FROM schedule 
                INNER JOIN section 
                ON class.id = section.class_id
                INNER JOIN faculty
                ON faculty.id = section.faculty_id
                INNER JOIN faculty
                ON faculty.id = office_hours.faculty_id
                INNER JOIN faculty_titles
                ON faculty_titles.faculty_id = faculty.id
                INNER JOIN faculty_education
                ON faculty_education.faculty_id = faculty.id 
                INNER JOIN section
                ON section.faculty_id = faculty.id 
                INNER JOIN class
                ON class.id = section.class_id
                INNER JOIN major_class_br
                ON major_class_br.class_id = class.id
                INNER JOIN  major_minor 
                ON major_class_br.major_minor_id = major_minor.id                
                 ");
      //execute query
      $result = mysql_query($query);

     if ($result){

    $totalhours = 0;

    while ($row = mysql_fetch_assoc( $result ))
    {  
        print "<b>" . $row['class_name'] . "</b><br>";
        print $row['class_caption'] . "<br>";
        print $row['class_description'] . "<br>";
        print $row ['class_credit_hours'] . "hrs. <br>";
        print "------------------------------<br />";
        $totalhours += $row['class_credit_hours']; 
    }   
    }

SQL 小提琴查詢

Answer 1

SELECT  class_name, class_caption, class_credit_hours, class_description
             FROM schedule 
            INNER JOIN section 
            ON class.id = section.class_id

這里有一個問題：您正在使用字段“class.id”進行內部聯接，但表“類”不在聯接的任一側。 所以它不會工作。

查詢應該像這樣開始：

SELECT  class_name, class_caption, class_credit_hours, class_description
             FROM class
            INNER JOIN section 
            ON class.id = section.class_id

然后使用表'schedule' 與它共享一個公共索引的表（我猜它是類）執行JOIN。

完整的查詢應該是這樣的：

SELECT  class.class_name, class.class_caption, class.class_credit_hours, class.class_description
            FROM class
            INNER JOIN section 
            ON class.id = section.class_id
            INNER JOIN faculty 
            ON faculty.id = section.faculty_id OR faculty.id = office_hours.faculty_id
            INNER JOIN faculty_titles
            ON faculty_titles.faculty_id = faculty.id
            INNER JOIN faculty_education
            ON faculty_education.faculty_id = faculty.id 
            INNER JOIN major_class_br
            ON major_class_br.class_id = class.id
            INNER JOIN major_minor 
            ON major_class_br.major_minor_id = major_minor.id
            INNER JOIN sched_sect_br 
            ON sched_sect_br.section_id =  section.id
            INNER JOIN schedule
            ON schedule.id = sched_sect_br.schedule_id
            INNER JOIN semester
            ON semester.id = schedule.semester_id
            INNER JOIN office_hours
            ON schedule.id = office_hours.schedule_id AND faculty.id = office_hours.faculty_id

此查詢從您在圖表中擁有的所有表中獲取信息，除了事件表之外，與任何其他表都不相關。 但是這個查詢仍然應該在 SELECT 上有更多的字段（你只是類表中的選擇字段，我知道你也想要其他 10 個表中的數據），要做到這一點，只需將“tablename.field”添加到SELECT 中的字段列表。