The object "DF__*" is dependent on column "*" - Changing int to double

The object 'DF_' is dependent on column '' - Changing int to double

Are you facing an issue when trying to change the data type of a column from int to double in your Entity Framework (EF) database? Don't worry, you're not alone! This is a common problem that many developers encounter. In this blog post, we will delve into the issue, provide easy-to-implement solutions, and empower you to overcome this obstacle. Let's dive in!

Understanding the Issue

When you attempt to update the database after changing the data type of a column from int to double, you might encounter the following error message:

The object 'DF_Movies_Rating_48CFD27E' is dependent on column 'Rating'.
ALTER TABLE ALTER COLUMN Rating failed because one or more objects access this column.

This error message essentially indicates that there is a default constraint (DF_*) set on the Rating column, and it is being referenced by another object within your database. As a result, the ALTER COLUMN operation fails.

Easy Solutions

Fortunately, there are a few straightforward solutions you can implement to overcome this issue.

Solution 1: Remove the Default Constraint

One way to resolve this problem is to remove the default constraint from the Rating column. Here's how you can do it:

-- Step 1: Find the name of the default constraint
SELECT name
FROM sys.default_constraints
WHERE parent_object_id = OBJECT_ID('YourTableName') AND type = 'D' AND parent_column_id = COLUMN_ID('Rating')

-- Step 2: Remove the default constraint
ALTER TABLE YourTableName DROP CONSTRAINT YourDefaultConstraintName

After performing these steps, you should be able to change the data type of the Rating column from int to double.

Solution 2: Create a New Column

If removing the default constraint is not a viable option for your particular scenario, you can create a new column with the desired data type (double), copy the data from the Rating column into the new column, and then drop the Rating column. Here's a step-by-step guide:

-- Step 1: Add the new column
ALTER TABLE YourTableName ADD NewRatingColumn DOUBLE

-- Step 2: Copy data from the Rating column to the new column
UPDATE YourTableName SET NewRatingColumn = CAST(Rating AS DOUBLE)

-- Step 3: Drop the old Rating column
ALTER TABLE YourTableName DROP COLUMN Rating

-- Step 4: Rename the new column to Rating (optional)
EXEC sp_rename 'YourTableName.NewRatingColumn', 'Rating', 'COLUMN'

By following these steps, you will successfully change the data type of the Rating column to double.

Let's Engage!

We hope that this blog post has shed light on the issue you were facing and provided you with simple solutions to overcome it. If you have any questions, suggestions, or have encountered other database-related obstacles, feel free to comment below or reach out to us on our social media channels. Let's engage and overcome challenges together!

Now it's your turn! Have you ever encountered an issue when changing a column's data type? Share your experience and how you solved it in the comments section below. Let's learn from each other and build a supportive tech community!

Happy coding! 👨‍💻🚀