tsql

问题 Trying to build a query. The input is ordered by rownumber in column 'rn' starting with 1 for each unique value in 'name' and defining a given sequence of entries in 'act'. In column 'act' it holds two values in multiple occurence, >sleep< and >wake<. The goal is to find for each consecutive set of rows of one of those values the minimum and maximum value of startt and endd. This shall be the input: name act rn startt endd ---------- ---------- ------ ------ ------ jimmy sleep 1 1 3 jimmy

问题 Is it possible to store or cache values that are part of one select column and then be used for the next one? For example, select FirstColumn = (complex query returns a value based on ThirdColumn), SecondColumn = (uses the same value returned from above + does some additional calculations.) from SomeTable Is it possible to do something like that so I don't have to write the same complex query twice? 回答1: You need CROSS APPLY here, it can refer to outer references, no annoying subqueries or

问题 I want generate number for every three rows CREATE TABLE #test(period INT) INSERT INTO #test VALUES (602),(603),(604),(605),(606),(607),(608),(609) I know we can generate sequence using row_number window function or while loop or cursor SELECT period, ( Row_number()OVER(ORDER BY period) - 1 ) / 3 + 1 FROM #test Result; +--------+-----+ | period | seq | +--------+-----+ | 602 | 1 | | 603 | 1 | | 604 | 1 | | 605 | 2 | | 606 | 2 | | 607 | 2 | | 608 | 3 | | 609 | 3 | +--------+-----+ Is there any

问题 This is my simplified statement SELECT ... FROM tab1 AS i FULL OUTER JOIN tab2 AS d ON i.[Id]=d.[Id] WHERE d.[Data]<>i.[Data] OR (d.[Data] IS NULL AND i.[Data] IS NOT NULL) OR (d.[Data] IS NOT NULL AND i.[Data] IS NULL) I want to get all entries that are i.[Data] is different from d.[Data] At least one value in table i or d is NOT NULL So I don't want to see records were and i and d contain the same data or are both NULL. My statement look so long and complicated. Is there an easier way?

问题 Here is a sample code of using the SqlDataReader : // Working with SQLServer and C# // Retrieve all rows cmd.CommandText = "SELECT some_field FROM data"; using (var reader = cmd.ExecuteReader()) { while (reader.Read()) { Console.WriteLine(reader.GetString(0)); } } EDIT : I mean I want to understand whether there is the same mechanism when retrieving data from database in a while-loop (in case of SqlDataReader ) as it does when working with the SQLite. // working with SQLite and Java if

问题 I need to shift data(columns) to left side if first columns(left side columns) have 0 value and NULL should be added in right side columns. Once non-zero value found in any columns then 0 value in later column should remain as it is. Input Data:- cust_id month1 month2 month3 month4 month5 c1 100 200 300 400 500 c2 0 0 50 250 350 c3 0 0 100 0 0 c4 100 0 100 0 500 c5 0 0 0 0 0 Expected Output Result:- cust_id month1 month2 month3 month4 month5 c1 100 200 300 400 500 c2 50 250 350 NULL NULL c3

问题 I have a database in which I have the following rows: ID | Date start | Date end ---------------------------------- a | 01-01-1950 | 30-01-1951 a | 01-01-1948 | 31-12-1949 a | 31-01-1951 | 01-06-2000 b | 01-01-1980 | 01-08-2010 c | 01-01-1990 | 31-12-2017 c | 31-01-1985 | 31-12-1989 What I got Multiple rows per person One start and end date per row In a not chronological order Select query which I want to return the following: ID | Date start 1 | Date end 1 | Date start 2 | Date end 2 | Date

问题 Imagine the following simple query, where I get a list of all users that were created within the last 3 days, the logic or example is not important SELECT ... , DATEDIFF(DAY, U.DateCreated, GETUTCDATE()) ... FROM dbo.AspNetUsers U WHERE DATEDIFF(DAY, U.DateCreated, GETUTCDATE()) < 3 I've repeated some code DATEDIFF(DAY, U.DateCreated, GETUTCDATE()) < 3 which, when I have much more complicated examples of the above I don't want to maintain twice or however many times I need that logic. How

问题 I have a query like: DECLARE @tmpValue SET @tmpValue = 0 -- it will be change SELECT * FROM Animal WHERE AniActive = 1 UNION IF @tmpValue > 0 SELECT * FROM Animal WHERE.Active = 0 When I use like this it is giving error because of if condition. I have to use UNION because of our structure. How can I use it with if condition? Thanks, John 回答1: Move the condition @tmpValue > 0 to the WHERE clause like so: SELECT * FROM Animal WHERE AniActive = 1 UNION SELECT * FROM Animal WHERE @tmpValue > 0

问题 I have a query like: DECLARE @tmpValue SET @tmpValue = 0 -- it will be change SELECT * FROM Animal WHERE AniActive = 1 UNION IF @tmpValue > 0 SELECT * FROM Animal WHERE.Active = 0 When I use like this it is giving error because of if condition. I have to use UNION because of our structure. How can I use it with if condition? Thanks, John 回答1: Move the condition @tmpValue > 0 to the WHERE clause like so: SELECT * FROM Animal WHERE AniActive = 1 UNION SELECT * FROM Animal WHERE @tmpValue > 0