The Not Null constraint specifies a column may not contain NULL values.


  • 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.

  • You can only define the Not Null constraint when creating a table; you cannot add it to an existing table. However, you can migrate data from your current table to a new table with the constraint you want to use.
    In the future we plan to support adding the Not Null constraint to existing tables.
  • For more information about NULL, see Null Handling.


You can only apply the Not Null constraint to individual columns.

CREATE TABLE table_name ( column_name column_type NOT NULL column_constraints , column_def table_constraints ) )
Parameter Description
table_name The name of the table you’re creating.
column_name The name of the constrained column.
column_type The constrained column’s data type.
column_constraints Any other column-level constraints you want to apply to this column.
column_def Definitions for any other columns in the table.
table_constraints Any table-level constraints you want to apply.

Usage Example

    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

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