Hi

It is dangerous to use hashbytes this way:

DataHashBytes AS HASHBYTES('MD5', (EmployeeName + CityName))

When EmployeeName = '' and CityName = 'Paris' and someone changes it to EmployeeName = 'Paris' and CityName = '' the hash stays the same. The solution (not very elegant but still a solution) is to use a delimiter, e.g.:

DataHashBytes AS HASHBYTES('MD5', (EmployeeName + char(0) + CityName))

The article is very useful, thank you.