where-clause

I'm entirely new at SQL, but let's say that on the StackExchange Data Explorer , I just want to list the top 15 users by reputation, and I wrote something like this: SELECT TOP 15 DisplayName, Id, Reputation, Reputation/1000 As RepInK FROM Users WHERE RepInK > 10 ORDER BY Reputation DESC Currently this gives an Error: Invalid column name 'RepInK' , which makes sense, I think, because RepInK is not a column in Users . I can easily fix this by saying WHERE Reputation/1000 > 10 , essentially repeating the formula. So the questions are: Can I actually use the RepInK "column" in the WHERE clause?

So I have managed to get this query working List<string> listStatus = new List<string>() ; listStatus.add("Text1"); List<string> listMerchants = new List<string>() ; listMerchants.add("Text2"); from item in db.vw_Dropship_OrderItems where listStatus.Contains(item.StatusCode) && listMerchants.Contains(item.MerchantId) select item; Here I would like to check if listStatus and listMerchants are not null only then put them inside WHERE clause. Like if listMerchants is null then query will be like where listStatus.Contains(item.StatusCode) I do not want to use switch or If condition. Thanks from

Today we currently have a statement like this: var Query = (from dp in db.Patients select dp); var UserID = User.Identity.GetUserId(); if (User.IsInRole("Administrator")) { Query = Query.Where(x => x.AdministratorID == UserID); } if (User.IsInRole("Counselor")) { Query = Query.Where(x => x.CounselorID == UserID); } if (User.IsInRole("Physician")) { Query = Query.Where(x => x.PhysicianID == UserID); } The problem is we have Users that can have multiple roles. If a User is both an Counselor and Physician we want the system to pull back all patients where CounselorID == UserID or PhysicianID ==

Is there a way I can improve this kind of SQL query performance: INSERT INTO ... WHERE NOT EXISTS(Validation...) The problem is when I have many data in my table (like million of rows), the execution of the WHERE NOT EXISTS clause if very slow. I have to do this verification because I can't insert duplicated data. I use SQLServer 2005 thx Make sure you are searching on indexed columns, with no manipulation of the data within those columns (like substring etc.) Off the top of my head, you could try something like: TRUNCATE temptable INSERT INTO temptable ... INSERT INTO temptable ... ... INSERT

I've been really digging into LINQ, and I'm trying to hash out this lambda expression business. I'm just not seeing the benefit of some of the nuances of the syntax. Primarily, it seems to me that a lambda expression is mostly just a different way of using a Where clause. Why wouldn't I just use a Where clause then? Is the lambda expression more efficient? Is it just another syntactical addition to draw programmers from another group to feel more comfortable in C#? Are there other better use cases for lambda expressions that I just haven't exposed to yet? Andreas Grech Take a look at this