#Sqlite foreign key multiple columns how to#

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.

Join exams on exams.exam_code = wrote_exam.exam_code Join wrote_exam on student.student_number = wrote_exam.student_number Or you could use JOIN.ON: select student.student_name, exams.exam_code. This means that if a column is set as a primary key, then this particular column.

#Sqlite foreign key multiple columns how to#

In this article let us see how to create a table with multiple foreign keys in MSSQL. There are two ways to delete a table from SQL: DROP and TRUNCATE. To check whether your current version of SQLite supports foreign key constraints or not, you use the following command. A table can have multiple foreign keys based on the requirement. The SQLite library must also be compiled with neither SQLITEOMITFOREIGNKEY nor SQLITEOMITTRIGGER. More specifically you do not have a cv.put (cv.put ( 4. SQLite has supported foreign key constraint since version 3.6.19. That is you do not provide the value of the respective column when inserting an Item. So the SQL from your comment should look more like this: select student.student_name, exams.exam_code. 1 Answer Sorted by: 0 It would appear that you are under the impression that SQLite will generate the foreign key values automatically. As you may know sqlite allows multiple column names in foreign key statement. You can see the id fields value are 0 and 1 respectively but the seq values are all 0. The SQLite syntax diagrams may be helpful: You can see there are two foreign keys in table Test and so there are two entries shown in PRAGMA foreignkeylist() output. I am using SQLite and DB Browser for SQLite. of users and two new columns age and lastname. When joining tables you almost always want to include an explicit join condition. Copy only the structure : columns, keys and indexes (expected on SQL Server which only. 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 Foreign keys are stored on one side of the relation. A foreign key is a primary key from another table. 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)) In SQL, you use a foreign key to create a relation between two tables. A SQLite FOREIGN KEY is a constraint used to link two tables. This means that if a parent record in TableB gets deleted, SQLite will cascade that deletion down to all child records in TableC.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 ( A composite key specifies multiple columns for a primary-key or foreign-key constraint. Whether the table is a WITHOUT ROWID table. A FOREIGN KEY consist of single or multiple columns in one table that refers to the.

Optionally, a generated column constraint. The SQLite FOREIGN KEY constraint is used to link two tables together. SQLite supports UNIQUE, NOT NULL, CHECK and FOREIGN KEY constraints.

The purpose of the constraint in the above table definition is that it links the tb_bid column as a foreign key pointing to the primary key id column in TableB. Both single column and composite (multiple column) primary keys are supported. For example, for TableC, you might use the following definition: CREATE TABLE TableC (ĬONSTRAINT fk_b FOREIGN KEY (tb_bid) REFERENCES TableB (id) ON DELETE CASCADE