Resolving Insertion Anomalies in SQL with Normalization

Resolving Insertion Anomalies in Database Design

Write a SQL query to resolve insertion anomalies in a poorly designed table.

Solution:

-- Poorly designed table with insertion anomalies.
CREATE TABLE Departments (
    DepartmentID INT PRIMARY KEY,
    ManagerID INT,
    ManagerName VARCHAR(100)
);

-- Resolve anomalies by separating manager details.
CREATE TABLE Managers (
    ManagerID INT PRIMARY KEY,
    ManagerName VARCHAR(100)
);

CREATE TABLE Departments_Normalized (
    DepartmentID INT PRIMARY KEY,
    ManagerID INT,
    FOREIGN KEY (ManagerID) REFERENCES Managers(ManagerID)
);

Explanation:

• Purpose of the Query :
• The goal is to resolve insertion anomalies by separating related attributes into their own tables.
• Key Components :
• Managers: Stores manager details independently.
• Departments_Normalized: Links departments to managers via a foreign key.
• Why Resolve Insertion Anomalies? :
• Insertion anomalies occur when inserting data requires unnecessary or incomplete information.
• Normalization ensures that all required data can be inserted without constraints.
• Real-World Application :
• In organizational databases, normalization avoids issues when assigning managers to departments.

Notes:

• Insertion anomalies are common in denormalized tables.
• Use normalization to simplify data entry and maintenance.
• Important Considerations:
• Ensure referential integrity when splitting tables.

For more Practice: Solve these Related Problems:

• Write a SQL query to resolve insertion anomalies in a table where department details and manager details are combined.
• Write a SQL query to redesign a table storing course details and instructor details to avoid insertion anomalies.
• Write a SQL query to normalize a table containing project details and team member details to resolve insertion anomalies.
• Write a SQL query to eliminate insertion anomalies in a table where product details and supplier details are stored together.

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