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Nullable subqueries should not be used in NOT IN conditions

Rule description

  • Nullable subqueries should not be used in NOT IN conditions

 

Non-compliant Code Example

CREATE TABLE Type1
(
    TypeId INT,
    TypeName VARCHAR(50),
    TypeCategory VARCHAR(50)
)
GO
CREATE TABLE Type2
( 
    TypeId INT,
    TypeName VARCHAR(50),
    TypeCategory VARCHAR(50)
)
GO

SELECT TypeId, TypeName, TypeCategory
FROM Type1  WHERE TypeId NOT IN (SELECT TypeId FROM Type2) --Non Compliant code (TypeId column might be null)

Compliant Code Example

CREATE TABLE Type1
(
    TypeId INT,
    TypeName VARCHAR(50),
    TypeCategory VARCHAR(50)
)
GO
CREATE TABLE Type2
( 
    TypeId INT IDENTITY(1,1) NOT NULL, -- Compliant code (Ensure that TypeId column is not null)
    TypeName VARCHAR(50),
    TypeCategory VARCHAR(50)
)
GO

SELECT TypeId, TypeName, TypeCategory
FROM Type1  WHERE TypeId NOT IN (SELECT TypeId FROM Type2)
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 VETSQLRULE5