![]() ![]() ![]() I just tested these SQLite foreign key examples on my system, using SQLite version 3.4.0, and they all work fine. A foreign key in SQL is a table-level construct that constrains one or more columns in that table to only allow values that are present in a different set. For example, I have two rows in table 1 with the same value in the referenced column. If the referenced column is also not unique, you have created a many-to-many relationship, which is a right pain to implement and can cause problems maintaining data integrity. A foreign key means that values in one table must also appear in. INSERT INTO customers VALUES (null, 'FOOBAR', '200 Foo Way', 'Louisville', 'KY', '40207') 2 Answers Sorted by: 3 The referencing column may not be unique, as you point out. A foreign key is a way to enforce referential integrity within your SQLite database. INSERT INTO customers VALUES (null, 'ACME, INC.', '101 Main Street', 'Anchorage', 'AK', '99501') INSERT INTO salespeople VALUES (null, 'Barney', 'Rubble', 10.0) INSERT INTO salespeople VALUES (null, 'Fred', 'Flinstone', 10.0) If you'd like to test this SQLite foreign key example in your own SQLite database, here's some sample data for each of these tables: I am working on a project with xamarin android using the library. Next, define a SQLite table that has two foreign keys, one that relates a new orders table back to the customers table, and a second foreign key that relates the orders table back to the salespeople table:įOREIGN KEY(customer_id) REFERENCES customers(id),įOREIGN KEY(salesperson_id) REFERENCES salespeople(id)Īs you can see, the SQLite foreign key syntax is very similar to other databases. To show how this works, first define two database tables that don’t have any foreign keys: (), SQLite supports foreign key constraints. SQLITETEMPSCHEMA works just like SQLITESCHEMA except that it is only visible to the application that created the temporary tables. Here’s a quick SQLite foreign key example. Temporary tables and their indices and triggers occur in another special table named SQLITETEMPSCHEMA. The SQLite database does support foreign keys, and its foreign key syntax is similar to other databases. The syntax of the SQL FOREIGN KEY constraint is: CREATE TABLE tablename ( column1 datatype, column2 datatype. SQLite foreign keys FAQ: Can you show me how to define foreign keys in a SQLite database table design? ![]()
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