You have a Microsoft Azure SQL Database instance.
The database contains a disk-based table named ContentTable that has 1 million rows and a column named Fax. Fax allows null values.
You need to update Fax to meet the following requirements:
✑ Prevent null values from being used.
✑ Always use an empty string instead of a null value.
Which statement or statements should you execute? (Each correct answer presents part of the solution. Choose all that apply.)
To ensure that null values are not allowed and that an empty string is used instead, you should first update all existing null values to an empty string. This can be done with the statement to set Fax = '' where Fax is null. Next, you should add a default constraint to set future inserts to an empty string if no value is provided. Thus, options A and E are correct. Option B is not appropriate here because altering the column to add the NOT NULL constraint directly will fail if current null values exist, and we already handled nulls and defaults with options A and E.
Answers are correct, but the explanation is a bit wrong - you need to set NOT NULL first, then set default value
Should be DEFAULT FIRST to prevent new record will not null UPDATE EMPTY NOT NULL