SQL Server NEWSEQUENTIALID() function is used to generate incremental unique values of type uniqueidentifier.
SQL Server ISNULL() Function is a system function that returns the specified value if the expression is NULL else it returns the expression.
SQL Server @@ERROR is a global variable that returns an error number if the last statement encountered an error but we have to trace it within just after the next line where the actual error occurred, otherwise, it will reset to 0.
SQL Server NEWID() function is a system function that is used to generate a unique value of type uniqueidentifier.
SQL Server @@IDENTITY function is a system function that is used to get the last IDENTITY value generated for any table with an identity column under the current session, regardless of the scope of the T-SQL statement that generated the value.
SQL Server ISNUMERIC( ) function is System Functions which is used to check if the expression is valid numeric type or not.