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The NOT NULL constraint specifies a column may not contain NULL values.
Details
INSERTorUPDATEstatements containingNULLvalues are rejected. This includesINSERTstatements that do not include values for any columns that do not have aDEFAULTvalue 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 NULLconstraint to an existing table column, use theALTER COLUMNstatement.For more information about
NULL, see NULL handling.
Syntax
You can only apply the NOT NULL constraint to individual columns.
| 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
> 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
