mysql - ERROR 1052 (23000): Column 'course_id' in where clause is ambiguous -

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i'm new mysql please tell me if question missing information,

i have query works fine:

select au.email, sm.created, sm.grade, sm.max_grade auth_user au, courseware_studentmodule sm sm.student_id = au.id , course_id = 'mycourse' , sm.module_type = 'problem';

but when want add column different table:

select au.email, sm.created, sce.created , sm.grade, sm.max_grade auth_user au, courseware_studentmodule sm,  student_courseenrollment sce sm.student_id = au.id , sm.student_id = sce.id , course_id = 'mycourse' , sm.module_type = 'problem';

i error 

error 1052 (23000): column 'course_id' in clause ambiguous

anyone know why?

thanks

this because column course_id present in more 2 tables.

write sm.course_id or sce.course_id , work.


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