How do I put a condition in the select statement in T-SQL

问题

A carer can provide support to two different service at the same Start time and End time this is called 1:2 Service type. The unique ID for this type of shift type are generated as the same unique ID for this type of service. I want to add 2 at the end of the unique ID for every second service. How do I find this? Bare in mind I am using this within the UNION with other 3 select statement. The first query above the Union is the one

My query below:

SELECT DISTINCT
CASE  
   WHEN SHIFT_CODE = '1:2 Support' 
      THEN '3'
      ELSE '' 
END [Datatype Id],
CAST(SS.Schedule_Subshift_ID AS VARCHAR(20)) + ' 1:2' [Unique Visit ID]

'' [Date],
'' [Start Time],
''+ ',' [End Time],
''+ ',,,' [Unique Client ID],
'' [Client Forename]

    FROM 

  Subshift

  UNION

SELECT DISTINCT
  CASE 
     WHEN CAST(CAST(EE.Start_Date_SK AS VARCHAR(255)) AS DATE) >= (GETDATE() - 41) 
      THEN ' 11 '
      ELSE ''
  END [DataTypeID],
 '' [Unique Visit ID],
 '' [Date],
 '' [Start Time],
 ''+ ',' [End Time],
 ''+ ',,,' [Unique Client ID],
 '' [Client Forename]
   FROM 
      Subshift

Result I get is:

Service    Unique Visit ID  Carer           Date        Start Time   End Time    SHIFT_PROPERTY_CODE
 Moira      211870 2          A         16/12/2019        19:00        22:00,      1:2 Support
 Marta      211870 2          A         16/12/2019        19:00        22:00,      1:2 Support
 Rebecca    211871 2          B         19/12/2019        19:00        22:00,      1:2 Support
 Elsie      211871 2          B         19/12/2019        19:00        22:00,      1:2 Support

Desired Result should be:

Service Unique Visit ID Carer Date Start Time End Time SHIFT_PROPERTY_CODE Moira 211870 A 16/12/2019 19:00 22:00, 1:2 Support Marta 211870 2 A 16/12/2019 19:00 22:00, 1:2 Support Rebecca 211871 B 19/12/2019 19:00 22:00, 1:2 Support Elsie 211871 2 B 19/12/2019 19:00 22:00, 1:2 Support

回答1:

You can try something along these lines:

SELECT 
  Case Row_Number() OVER (Partition By SS.Schedule_Subshift_ID Order By ClientName) 
   when 1 then S.Schedule_Subshift_ID
   when 2 then S.Schedule_Subshift_ID + ' 2'
   end
FROM Subshift

You can partition by service id and order by time for example, I don't exactly understand your case. Please keep in mind that the Query you copied DOES NOT result in the result sets below. So if you want me to be more specific - please provide the proper query.

来源：https://stackoverflow.com/questions/59787550/how-do-i-put-a-condition-in-the-select-statement-in-t-sql

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sql

tsql

concatenation