SQL错误错误：列“ pk1”指定了多次

Question

Any help? I can't find where the duplication is happening:

SELECT * 
FROM attempt 
INNER JOIN gradebook_grade GRADES 
    on(ATTEMPT.gradebook_grade_pk1=GRADES.pk1 )
INNER JOIN gradebook_main GRADES_TITLE 
    on (GRADES.gradebook_main_pk1 = GRADES_TITLE.pk1) 
INNER JOIN course_main Course 
    on (GRADES_TITLE.crsmain_pk1= Course.pk1)  
LEFT JOIN mainJoinedTable2 ENROLLMENT 
    ON (Enrollment.course_users_pk1 = GRADES.course_users_pk1)

Answer 1

You have pk1 column multiple tables so you have to specify which tables pk1 you are going to project in select statement , so you can Try like below

 SELECT attempt .* ,GRADES.*,Course.*
    FROM attempt 
    INNER JOIN gradebook_grade GRADES 
        on(ATTEMPT.gradebook_grade_pk1=GRADES.pk1 )
    INNER JOIN gradebook_main GRADES_TITLE 
        on (GRADES.gradebook_main_pk1 = GRADES_TITLE.pk1) 
    INNER JOIN course_main Course 
        on (GRADES_TITLE.crsmain_pk1= Course.pk1)  
    LEFT JOIN mainJoinedTable2 ENROLLMENT 
        ON (Enrollment.course_users_pk1 = GRADES.course_users_pk1)

Answer 2

Quick search brought me there : View error in PostgreSQL

Basically, you join many tables that have identical column names (in your instance, at least the following : gradebook_grade.pk1 , course_main.pk1 , gradebook_main.pk1 ). The fact that you SELECT * makes it so the output will have many pk1 columns and that will be ambiguous. You need to specify each column in your SELECT and rename them with aliases.