Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
I am cloning and extending the Google Tasks application. I want to be able to store the rows order. I have created a field in the database, named rowNumber. When the user inserts a row in the middle of others, I have to update this field in many other rows to achieve the desired output. There is a better way to do it?
BTW the application is made for the Google AppEngine (Python).
Make rowNumber a floating point number. When user inserts between rows x and y, the new row gets rowNumber = (x.rowNumber + y.rowNumer) / 2.
When you want to move a row, just update its rowNumber the same way based on target position.
New rows get rowNumber eg. MAX + 256.
Edit Microsoft solved this in SQL Server 2008 using new HierarchyId datatype. You can insert between 2 items almost as many times as you want – until you run out of HierarchyId max size.