1

私には、student_id、house_id などの フィールドとsubjects、houses、students_subjectsを持つテーブル名の学生がいます。

私はこのクエリを使用しています

SELECT students_subjects.student_id,students.house_id,students_subjects.subject_id,subjects.subject_name,students.rollno,students.first_name, students.last_name FROM 
students_subjects LEFT JOIN students on students_subjects.student_id=students.id
LEFT JOIN subjects on students_subjects.subject_id=subjects.id  WHERE students_subjects.class_years_section_id=1

これは私にとってはうまく機能しています..

今、家のテーブルから家の名前も取得したい

このクエリを試しました

SELECT students_subjects.student_id,students.house_id,houses.house_name, students_subjects.subject_id,subjects.subject_name,students.rollno,students.first_name, students.last_name FROM 
students_subjects LEFT JOIN students on students_subjects.student_id=students.id
LEFT JOIN subjects on students_subjects.subject_id=subjects.id

LEFTJOINはstudents.house_id=houses.idに家を建てますWHEREStudents_subjects.class_years_section_id= 1

AND students_subjects.school_session_id=1 AND students.is_active=1

そしてそれは私にhouse_name=NULLを与えます

家の名前も教えてもらえますか？結合クエリを使用する

ありがとう

4

2 に答える 2

7

クエリのエラーは、 after句のLEFT JOINキーワードが原因で発生します。WHERE

SELECT  students_subjects.student_id,
        students.house_id,
        students_subjects.subject_id,
        subjects.subject_name,
        students.rollno,
        students.first_name, 
        students.last_name 
FROM    students_subjects 
        LEFT JOIN students 
            on students_subjects.student_id=students.id
        LEFT JOIN subjects 
            on students_subjects.subject_id=subjects.id
        LEFT JOIN houses 
            on students.house_id=houses.id
WHERE   students_subjects.class_years_section_id = 1 AND 
        students_subjects.school_session_id = 1 AND 
        students.is_active = 1

JOINsはFROM句の一部であることを忘れないでください。

更新1

SELECT  b.student_id,
        a.house_id,
        b.subject_id,
        c.subject_name,
        a.rollno,
        a.first_name, 
        a.last_name,
        d.house_name            
FROM    students a
        INNER JOIN students_subjects b
            ON b.student_id = a.id
        INNER JOIN subjects  c
            ON b.subject_id = c.id
        INNER JOIN houses d
            ON a.house_id = d.id
WHERE   b.class_years_section_id = 1 AND 
        b.school_session_id = 1 AND 
        a.is_active = 1
于 2013-03-18T05:10:28.267 に答える
0

句を配置し忘れた場合は、次のWHEREようにしてください。

SELECT students_subjects.student_id,students.house_id,students_subjects.subject_id,subjects.subject_name,students.rollno,students.first_name, students.last_name 
FROM students_subjects 
     LEFT JOIN students ON students_subjects.student_id=students.id
     LEFT JOIN subjects ON students_subjects.subject_id=subjects.id  
     LEFT JOIN houses ON students.house_id=houses.id
WHERE students_subjects.class_years_section_id=1 
AND students_subjects.school_session_id=1 AND students.is_active=1
于 2013-03-18T05:14:16.530 に答える