NOT NULL constraint

On this page

The NOT NULL constraint specifies a column may not contain NULL values.

Details

• INSERT or UPDATE statements containing NULL values are rejected. This includes INSERT statements that do not include values for any columns that do not have a DEFAULT value constraint.

For example, if the table foo has columns a and b (and b does not have a DEFAULT VALUE), when you run the following command:

  > INSERT INTO foo (a) VALUES (1);

CockroachDB tries to write a NULL value into column b. If that column has the NOT NULL constraint, the INSERT statement is rejected.

• To add the NOT NULL constraint to an existing table column, use the ALTER COLUMN statement.

• For more information about NULL, see NULL handling.

Syntax

You can only apply the NOT NULL constraint to individual columns.

Usage example

> CREATE TABLE IF NOT EXISTS customers (
    customer_id INT         PRIMARY KEY,
    cust_name   STRING(30)  NULL,
    cust_email  STRING(100) NOT NULL
  );

> INSERT INTO customers (customer_id, cust_name, cust_email) VALUES (1, 'Smith', NULL);

pq: null value in column "cust_email" violates not-null constraint

> INSERT INTO customers (customer_id, cust_name) VALUES (1, 'Smith');

pq: null value in column "cust_email" violates not-null constraint

See also

• Constraints
• DROP CONSTRAINT
• CHECK constraint
• DEFAULT constraint
• REFERENCES constraint (Foreign Key)
• PRIMARY KEY constraint
• UNIQUE constraint
• SHOW CONSTRAINTS
• NULL HANDLING

Was this helpful?