比较SQL Server中的两个值

Question

I'm trying to get the value that arrived last between two sets. This is the code im developing

USE KronosNET22
GO

Select distinct 
    dbo.[Object].Name, dbo.[ObjectSignal_2016_07_22].Code,
    MAX(dbo.[ObjectSignal_2016_07_22].TimeIn) as tiempo
from 
    dbo.[Object],dbo.[ObjectSignal_2016_07_22]
where 
    dbo.[Object].IdClient = '6C74F97C-7253-415D-96B1-4B902D8334D7'
    and (dbo.[ObjectSignal_2016_07_22].Code = 'ON3' or 
         dbo.[ObjectSignal_2016_07_22].Code = 'OFF3' or 
         dbo. [ObjectSignal_2016_07_22].Code = 'E401' or 
         dbo.[ObjectSignal_2016_07_22].Code = 'R401')
    and dbo.[Object].Name = dbo.[ObjectSignal_2016_07_22].ObjectName
group by 
    dbo.[Object].Name, dbo.[ObjectSignal_2016_07_22].Code
order by 
    dbo.[Object].Name, MAX(dbo.[ObjectSignal_2016_07_22].TimeIn) desc

and this is the result I'm getting

AV CHILE PORCIUNCULA    ON3 1469211062
AV CHILE PORCIUNCULA    OFF3    1469195866
CALIMA  ON3 1469230879
CALIMA  OFF3    1469217492
CAMPANARIO POPAYAN  ON3 1469210662
CAMPANARIO POPAYAN  OFF3    1469203155
EL PROGRESO -- DOS QUEBRADAS    OFF3    1469194694
EL PROGRESO -- DOS QUEBRADAS    ON3 1469146950
EXITO -- SUBA   ON3 1469214392
EXITO -- SUBA   OFF3    1469199388
MEGACITY ZIPAQUIRA  OFF3    1469194774
MERCURIO    ON3 1469231767
MERCURIO    OFF3    1469198081
METROPOLITANO   ON3 1469228672
METROPOLITANO   OFF3    1469225061
NIZA    OFF3    1469218151
NIZA    ON3 1469214985
PLATINO     ON3 1469228261
PLATINO     OFF3    1469217680
PORTAL DEL PRADO    OFF3    1469147653
TITAN PLAZA OFF3    1469213346
TITAN PLAZA ON3 1469211705

How can I make that only appear the higher value so I do no get two values for the same place.

Answer 1

You really should start using the ANSI-92 style joins. They have been around for over 20 years now. Those comma separated table names are a bad habit.

• Bad habits to kick : using old-style JOINs

There is no point in using distinct and group by in the same query.

You also should use aliases to make your queries a lot more legible. As for your actual question you can use ROW_NUMBER. Something like this should be pretty close.

with MySortedResults as
(
    Select 
        o.Name
        , os.Code
        , os.TimeIn as tiempo
        , ROW_NUMBER() over (partition by o.Name order by os.TimeIn desc) as RowNum
    from dbo.[Object] o
    join dbo.[ObjectSignal_2016_07_22] os on o.Name = os.ObjectName
    where 
        o.IdClient = '6C74F97C-7253-415D-96B1-4B902D8334D7'
        and os.Code IN ('ON3', 'OFF3', 'E401', 'R401')    
)   

select sr.Name
    , sr.Code
    , sr.tiempo
from MySortedResults sr
where sr.RowNum = 1
order by sr.Name