- #Sqlite foreign key insert statements how to#
- #Sqlite foreign key insert statements update#
- #Sqlite foreign key insert statements code#
I just tested these SQLite foreign key examples on my system, using SQLite version 3.4.0, and they all work fine. INSERT INTO customers VALUES (null, 'FOOBAR', '200 Foo Way', 'Louisville', 'KY', '40207') INSERT INTO customers VALUES (null, 'ACME, INC.', '101 Main Street', 'Anchorage', 'AK', '99501') INSERT INTO salespeople VALUES (null, 'Barney', 'Rubble', 10.0) Note that this setting is not required for creating foreign keys, but it is required for enforcing foreign keys. If you open another connection, you’ll need to run the same statement for that connection. INSERT INTO salespeople VALUES (null, 'Fred', 'Flinstone', 10.0) To do this, run the following statement: PRAGMA foreignkeys ON This will enable foreign key enforcement for your database connection. 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: 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. See also: langaltertable.html langcreatetable.html. Used by: column-constraint table-constraint.
#Sqlite foreign key insert statements update#
To show how this works, first define two database tables that don’t have any foreign keys: REFERENCES foreign-table ( column-name ), ON DELETE SET NULL UPDATE SET DEFAULT CASCADE RESTRICT NO ACTION MATCH name NOT DEFERRABLE INITIALLY DEFERRED INITIALLY IMMEDIATE. Here’s a quick SQLite foreign key example. The SQLite database does support foreign keys, and its foreign key syntax is similar to other databases.
#Sqlite foreign key insert statements how to#
If the table contains data that you want to keep, you can transfer that data to another table, before transferring it back once you’ve created the new table with the foreign key constraint.SQLite foreign keys FAQ: Can you show me how to define foreign keys in a SQLite database table design? Therefore, if you need to add a foreign key to an existing table, you’ll need to drop the table and create it again with the foreign key constraint. The ALTER TABLE statement in SQLite is very limited, and it doesn’t allow for adding a foreign key to an existing table. Adding a Foreign Key to an Existing Table As mentioned, you’ll need to enable foreign key support before your foreign keys will be enforced. If you don’t get this error, and the data was successfully inserted, you haven’t enabled foreign key support. It therefore, helped us maintain data integrity. So our foreign key successfully prevented bad data from entering the database. Result: Error: FOREIGN KEY constraint failed a TypeId value that doesn’t exist in the Types column). Let’s try to add a pet that uses a non-existent TypeID (i.e. sqlite> SELECT * FROM Pets īut now let’s try inserting data that violates the foreign key. The tables now contain the data shown above. Now that our tables have been created with the appropriate foreign key, we can add data. In this case it will reference the TypeId column of the Types table. The REFERENCES Types(TypeId) specifies the column that our foreign key will reference.
The FOREIGN KEY(TypeId) part declares Pets.TypeId as the foreign key.Īlthough I didn’t qualify the column name with its table name, we know it’s Pets.TypeId (and not Types.TypeId) because we’re running this in the CREATE TABLE statement for Pets. The part that creates the foreign key is this: FOREIGN KEY(TypeId) REFERENCES Types(TypeId)
CREATE TABLE Types(įOREIGN KEY(TypeId) REFERENCES Types(TypeId)
#Sqlite foreign key insert statements code#
We can use the following code to create these two tables. In this example we’ll make it the primary key. While parent keys are usually also the primary key for the table, this is not actually a requirement. In other words, we want to make Pets.TypeId the child key (with a foreign key constraint), and Types.TypeId the parent key (with a primary key constraint). Imagine we want two tables with the following data.Īnd we want the TypeId column of the Pets table to reference the TypeId column of the Types table. Now that we’ve enabled foreign key support, let’s go ahead and create a foreign key. SQLite users should be aware of some caveats when using bulk inserts.
Note that this setting is not required for creating foreign keys, but it is required for enforcing foreign keys. When a model has a foreign key, you can directly assign a model instance to the. This will enable foreign key enforcement for your database connection. To do this, run the following statement: PRAGMA foreign_keys = ON The first thing we should do is to enable foreign key support (if it hasn’t already been done).Īssuming your SQLite library hasn’t been compiled with SQLITE_OMIT_FOREIGN_KEY or SQLITE_OMIT_TRIGGER defined, you will still need to enable foreign key support at runtime. This article provides an example of creating a foreign key when creating a table in SQLite. When you create a table in SQLite, you can also create a foreign key in order to establish a relationship with another table.
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