DF190: No nullability constraint is specified for table column.
Last modified: May 28, 2025
The topic describes the DF190 T-SQL code analysis rule.
Category
BEST PRACTICE
Message
No nullability constraint is specified for table column.
Description
It is recommended to explicitly specify the nullability of table columns when creating a table, declaring a temporary table, or defining a table variable.
Additional information
By following this rule, you provide clarity about the expected behavior of the columns regarding null values, which enhances the understanding of the table structure and facilitates data integrity. Additionally, explicitly defining nullability helps prevent potential errors and inconsistencies in data manipulation operations.
Noncompliant code example
CREATE TABLE dbo.DemoTable(Code VARCHAR(128))
GO
Compliant solution
CREATE TABLE dbo.DemoTable(Code VARCHAR(128) NULL)
GO
CREATE TABLE dbo.DemoTable(Code VARCHAR(128) NOT NULL)
GO
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