How to change the DEFAULT value for a column

###First, drop the existing default constraint if necessary If the column already has a default value, we can get the existing default constraint name from the Table Designer or DDL.

And then we need to drop the constraint using the command shown below:

ALTER TABLE dbo.YouTableName DROP CONSTRAINT TheExistingConstrainName;

###Add a new default constraint

ALTER TABLE dbo.YouTableName ADD CONSTRAINT YourNewConstraintName
DEFAULT YourNameDefaultValue FOR YourColumnName;

Alternatively, you can reuse the TheExistingConstraintName instead of YourNewConstrainName

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