SQLite treats all NULL values are different, therefore, a column with a UNIQUE constraint can have multiple NULL values. Here is the error: Error while executing SQL query on database 'chinook': `UNIQUE` constraint failed: shapes.background_color, shapes.foreground_colorĬode language: SQL (Structured Query Language) ( sql ) SQLite UNIQUE constraint and NULL However, the following statement causes an error due to the duplicates in both background_color and foreground_color columns: INSERT INTO shapes(background_color,foreground_color) The following statement works because of no duplication violation in both background_color and foreground_color columns: INSERT INTO shapes(background_color,foreground_color) The following statement inserts a new row into the shapes table: INSERT INTO shapes(background_color,foreground_color) UNIQUE(background_color,foreground_color)
The following statement creates the shapes table with a UNIQUE constraint defined for the background_color and foreground_color columns: CREATE TABLE shapes( Here is the error message: Error while executing SQL query on database 'chinook': UNIQUE constraint failed: contacts.emailĬode language: SQL (Structured Query Language) ( sql ) Defining a UNIQUE constraint for multiple columns example VALUES ( 'Johnny', 'Doe', language: SQL (Structured Query Language) ( sql )
If you attempt to insert a new contact with the same email, you will get an error message: INSERT INTO contacts(first_name,last_name,email) VALUES ( 'John', 'Doe', language: SQL (Structured Query Language) ( sql )
The following example inserts a new row into the contacts table: INSERT INTO contacts(first_name,last_name,email) The following statement creates a new table named contacts with a UNIQUE constraint defined for the email column: CREATE TABLE contacts( Defining a UNIQUE constraint for one column example Let’s take some examples of using the UNIQUE constraint.
Sqlite insert duplicate to unique update#
Once a UNIQUE constraint is defined, if you attempt to insert or update a value that already exists in the column, SQLite will issue an error and abort the operation.
Sqlite insert duplicate to unique how to#
The following illustrates how to define a UNIQUE constraint for multiple columns: CREATE TABLE table_name( Or at the table level: CREATE TABLE table_name( The following shows how to define a UNIQUE constraint for a column at the column level: CREATE TABLE table_name(Ĭode language: SQL (Structured Query Language) ( sql ) Only at the table level, you can define a UNIQUE constraint across multiple columns. You can define a UNIQUE constraint at the column or the table level. To define a UNIQUE constraint, you use the UNIQUE keyword followed by one or more columns. Introduction to SQLite UNIQUE constraintĪ UNIQUE constraint ensures all values in a column or a group of columns are distinct from one another or unique. Other variations on excluded.id that I've tried either don't exist or don't work.Summary: in this tutorial, you will learn how to use the SQLite UNIQUE constraint to ensure all values in a column or a group of columns are unique. Sqlite> INSERT INTO bar (key, fooID) SELECT 'key', foo.id FROM foo WHERE foo.name='two' ON CONFLICT (bar.key) DO UPDATE SET fooID=excluded.id Sqlite> INSERT INTO bar (key, fooID) SELECT 'key', foo.id FROM foo WHERE foo.name='three' ON CONFLICT (bar.key) DO UPDATE SET fooID=excluded.id in the above contrived example if I go from using 'three' for foo.name to 'two' it updates fine, but if I then run again with 'three' it does not update. ON CONFLICT (key) DO UPDATE SET fooID=excluded.id īut it only sometimes seems to update the existing row, eg. SELECT 'key', foo.id FROM foo WHERE foo.name='three' If I want to insert into a value into the table bar (here represented by the 'key' string, but in the real world it would be parameterized and this would be $1 and the 'three' would be $2) using the name field from foo I tried something like the following: INSERT INTO bar (key, fooID) INSERT INTO foo (name) VALUES ('one'), ('two'), ('three') įOREIGN KEY (fooID) REFERENCES foo(id) ON DELETE CASCADE, Assuming a database built with the following: PRAGMA foreign_keys = ON
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