I am not able to understand what Range / primary key is here in the docs on Working with Tables and Data in DynamoDB How does it work? What do they mean by “unordered hash index on the hash attribute and a sorted range index on the range attribute”? 4 Answers 4
I’m using mysql database. I have a confusion between primary key and unique key. Please help me where should I create primary and unique key. I mean in which situation we create unique key or primary key . 15 Answers 15
As the title, I have an existing table which is already populated with 150000 records. I have added an Id column (which is currently null). I’m assuming I can run a query to fill this column with incremental numbers, and then set as primary key and turn on auto increment. Is this the correct way … Read more
Closed. This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 5 months ago. The community reviewed whether to reopen this question 5 months ago and left it closed: Original close reason(s) were … Read more
Can I have multiple primary keys in a single table? 12 Answers 12
What’s the Hi/Lo algorithm? I’ve found this in the NHibernate documentation (it’s one method to generate unique keys, section 5.1.4.2), but I haven’t found a good explanation of how it works. I know that Nhibernate handles it, and I don’t need to know the inside, but I’m just curious. 5 s 5
I am using Entity Framework 1 with .net 3.5. I am doing something simple like this: var roomDetails = context.Rooms.ToList(); foreach (var room in roomDetails) { room.LastUpdated = DateTime.Now; } I am getting this error when I try to do: context.SaveChanges(); I get the error: Unable to update the EntitySet – because it has a … Read more
I ran into the problem that my primary key sequence is not in sync with my table rows. That is, when I insert a new row I get a duplicate key error because the sequence implied in the serial datatype returns a number that already exists. It seems to be caused by import/restores not maintaining … Read more
What is the syntax for specifying a primary key on more than 1 column in SQLITE ? 9 s 9 According to the documentation, it’s CREATE TABLE something ( column1, column2, column3, PRIMARY KEY (column1, column2) );
I started by googling and found the article How to write INSERT if NOT EXISTS queries in standard SQL which talks about mutex tables. I have a table with ~14 million records. If I want to add more data in the same format, is there a way to ensure the record I want to insert … Read more
