sql-order-by

问题 i'm a bit stomped.. I'm trying to achieve a fairly simple logic.. I have a "user_sessions" table with log_in and log_out (int, epoch time stamps) userID | log_in | log_out trying to show the RECENT activities, I need to list all the sessions in DESCENDING ORDER based on the LATEST ACTIVITY, and this could either be log_in or log_out.. and this is where i'm stomped. I tried different ORDER and SORT methods... I'm just not getting it. 回答1: SELECT * FROM user_sessions ORDER BY GREATEST(log_in,

问题 I have data as below ID Name Description DataSource Year 1 Apple Sweet & Tasty Source_A 2016 1 Apple Red and Sweet & Tasty Source_B 2015 2 Apple Delicious Source_A 2016 2 Apple Delicious and Red Source_C 2015 3 Apple Source_C 2013 3 Apple Green and Large Source_B 2016 In my case, I would like to give priority to source_B because it is more reliable. So if there is a data from Soure_B, I would like to display that row for the specific ID and ignore others. If data from source_B is not present,

问题 I have a rails app. I would like to display user profiles ordered by the number of the common tasks they have with the current user. Every task has one assigner and one executor. The number should include both the executed_tasks and assigned_tasks for the same user. So for example if current_user assigned 5 tasks to User4 and User4 assigned 3 tasks to current_user then this number would be 8. My main problem is that I don't know how to use the given user as arg for the count. Should I do in

问题 This is weird to me: One table 'ACTIVITIES' with one index on ACTIVITY_DATE. The exact same query with different LIMIT value results in different execution plan. Here it is: mysql> explain select * from ACTIVITIES order by ACTIVITY_DATE desc limit 20 -> ; +----+-------------+------------+-------+---------------+-------------+---------+------+------+-------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+------------+-------+-------

问题 I a lot of orders in my Factory . Our regular time to finish our job is 10 days but sometimes we promise to the customer that it will be shorter (lets assume 5 days). I tried to build an SQL that order by the minimum Date of the two columns : SELECT id, Status, DeliveryDate, PromiseDate FROM CustomerOrderT WHERE Status > 2 and Status <7 ORDER BY CASE WHEN DeliveryDate > PromiseDate then PomiseDate ELSE DeliveryDate END; But i get a problem message from ms access. maybe write it correctly The

问题 I would like to return a set that is grouped by ID_F, limited in count within ID_F and sorted by date within ID_F Here is my database setup: CREATE TABLE [dbo].[U]( [ID] [uniqueidentifier] NOT NULL, [Name] [nvarchar](max) NULL, CONSTRAINT [PK_U] PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[F]( [ID] [uniqueidentifier] NOT NULL, [Name]

问题 I am trying to sort some Nagios alerts in MySQL. I would like column 2 to be grouped together as it is now. All alerts are grouped. The problem is that i would like those groups to be in descending order. For example, "All Hosts | All Events | 65 |" should be at the top, next would be "All Hosts | memory-usage-UNX | 25", this would be followed by the 25 memory-usage-UNX alerts. Next would be "All Hosts | CPU-Load-UNX | 9" and then the rest of the CPU-Load-UNX alerts in descending order based

问题 I have a query to select posts ( wp_posts table ) where either 1 key/value pair or another is present on the a second table ( wp_postmeta ). Esentially, this works, but I then need to order the results by the first key/pair value ( department_head ), and then the second ( staff_surname ). The problem is, becuause of the way the results are grabbed by the query, there is no department_head key to use to order the results by. I'm guessing that this is because the query is finding the staff

问题 This query always returns the same amount of rows but, in a different order, every time. Why does this happen? I have more filters to add but I can't get past this step. BEGIN DECLARE @lastStatus Varchar(10) SELECT [Job].[Job], [Job].[Part_Number], [Job].[Rev], [Job_Operation].[Description], [Job].[Customer_PO], [Job].[Customer_PO_LN], [Delivery].[Promised_Date], [Job_Operation].[Operation_Service], [Job].[Note_Text], [Job_Operation].[Status], [Job_Operation].[Sequence] INTO [#tmpTbl] FROM

问题 I have a problem with creating select query ordered by following logic: SELECT * FROM Products WHERE 1 ORDER BY Stock > 0, Price DESC Table sample: +---------+-------+-------+ | Product | Price | Stock | +---------+-------+-------+ | Car | 3500 | 30 | | Boat | 7500 | 6 | | Bike | 150 | 220 | | Plane | 55000 | 0 | +---------+-------+-------+ The desired result is, that the table will be ordered by price if the stock value is greater than 0. So the result should be: +---------+-------+-------+