This script identifies a column's default constraint (if any) and drops it:
DECLARE @sql NVARCHAR(MAX) SELECT @sql = 'ALTER TABLE [' + s.name + '].[' + o.name + '] DROP CONSTRAINT [' + dc.name + ']' FROM sys.schemas s INNER JOIN sys.objects o ON o.schema_id = s.schema_id INNER JOIN sys.columns c ON c.object_id = o.object_id INNER JOIN sys.default_constraints dc ON dc.parent_object_id = o.object_id AND dc.parent_column_id = c.column_id WHERE s.name = 'schemaName' AND o.name = 'tableName' AND c.name = 'columnName' PRINT @sql EXEC(@sql)