How to add a new Column to an Existing SQL Table

Add a New Column

Write a SQL query to add a new column to an existing table.

Solution:

-- Add a new column "Department" to the "Employees" table.
ALTER TABLE Employees
ADD Department VARCHAR(50); -- Add a column to store department names.

Explanation:

1. Purpose of the Query :

1. The goal is to add a new column named Department to the Employees table.
2. This demonstrates how to use the ALTER TABLE statement to modify the structure of an existing table by adding a new column.

2. Key Components :

1. ALTER TABLE Employees : Specifies the table to be modified.

2. ADD Department VARCHAR(50) : Adds a new column named Department with a data type of VARCHAR(50), which can store department names up to 50 characters long.

3. Why use ALTER TABLE? :

1. Adding a new column is useful when you need to store additional information in an existing table without recreating it.
2. For example, if you decide to track the department each employee belongs to, you can add a Department column to the Employees table.

4. Real-World Application :

1. For example, in a company database, you might initially create the Employees table without a Department column but later realize that tracking department information is necessary. Adding this column allows you to store and manage department-related data.

Additional Notes:

• Adding columns is part of adapting a database to changing requirements.
• Scenarios where adding a column is appropriate, such as:
• Expanding the table to include new attributes (e.g., department, location, or role).
• Supporting new features or reports in the application.
• Important Considerations :
• Ensure that the new column's data type aligns with the type of data it will store.
• Adding a column does not affect existing rows unless a default value is specified.

For more Practice: Solve these Related Problems:

• Write a SQL query to add a new column named phone_number to an existing table called customers.
• Write a SQL query to add a new column named created_at with a default value of the current timestamp to a table named orders.
• Write a SQL query to add a new column named is_active with a BOOLEAN data type to a table named users.
• Write a SQL query to add a new column named discount_rate with a DECIMAL data type to a table named products.

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• SQL Data Definition Language (DDL) Exercises Home ↩
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