Note that I've also added some table qualifiers to the columns in your SELECT clause, those are needed to uniquely specify which exam_code you're interested in and since one column needs to be qualified, I did them all for consistency in real life I'd prefix them all to make things nice and explicit.Īlso, I don't see a student_location anywhere, perhaps you mean student.student_address or exams.exam_location. Then add where conditions to filter the results as needed. In other words, a foreign key is a column or a combination of columns that is used to establish and enforce a link between the data in two tables. CREATE TABLE students ( id INTEGER NOT NULL, studentname TEXT NOT NULL, PRIMARY KEY (id) ) CREATE TABLE houses ( id INTEGER NOT NULL, housename TEXT. Below is my schema, the 'assignments' table just serves to assign students' houses to them. A foreign key uses to enforce the relationships between two or more tables in SQLite database. Join exams on exams.exam_code = wrote_exam.exam_code This is a part of a CS50 practice problem where I have to read data from a. Join wrote_exam on student.student_number = wrote_exam.student_number Or you could use JOIN.ON: select student.student_name, exams.exam_code. So the SQL from your comment should look more like this: select student.student_name, exams.exam_code. The SQLite syntax diagrams may be helpful: When joining tables you almost always want to include an explicit join condition. This is a sample data inserted into tables : STUDENT_NAME : JohnĪ) output student names, exam codes and student location, who wrote the examī) output exam code, exam subject and exam location for student with ID : 123456789 STUDENT_NUMBER INTEGER PRIMARY KEY NOT NULL,Īnd a table for EXAMS : CREATE TABLE EXAMS(Īnd a table called WROTE_EXAM to get the information for students who wrote a specific exam CREATE TABLE WROTE_EXAM (įOREIGN KEY(STUDENT_NUMBER) REFERENCES STUDENT(STUDENT_NUMBER),įOREIGN KEY(EXAM_CODE) REFERENCES EXAMS(EXAM_CODE)) The SQLite foreign key is a basic that checks the presence of a huge worth present in one table to another table that has an association with the essential. Therefore, most EF Core models also layer 'navigations' over the FK representation. I want to select result in sqlite from multiple tables with multiple foreign keys, I tried JOIN but it did not work that well for example :Ī table for STUDENT : CREATE TABLE STUDENT ( Foreign keys are a good way to store and manipulate relationships in the database, but are not very friendly when working with multiple related entities in application code.
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