如果列为空或空，则SQL Server存储过程替换空字符串

Question

I need to check to see if a certain coloumn in my stored proc is either empty or null.

This is a snippet of what I have right now:

SELECT * , 
CASE WHEN a.USER IS NULL
    THEN b.ROLE
    ELSE ISNULL(a.FirstName,'') + ' ' + (ISNULL(a.MiddleName+' ','') + ISNULL(a.LastName,'')
END AS 'CustomerName'

I am checking to see if a.MiddleName is NULL but how do I also check to see if its empty and if its empty to just insert a empty string (no space)?

Thanks

Answer 1

Change to

SELECT 
    * , 
    CASE 
       WHEN a.USER IS NULL
         THEN b.ROLE
         ELSE CASE 
                WHEN ISNULL(a.MiddleName, '') = '' 
                  THEN ISNULL(a.FirstName,'') + ' ' + ISNULL(a.LastName,'')

                  ELSE ISNULL(a.FirstName,'') + ' ' + a.MiddleName + ' ' + ISNULL(a.LastName,'')
              END
    END AS 'CustomerName'

Answer 2

Another sollution is:

SELECT * , 
CASE WHEN a.USER IS NULL
THEN b.ROLE
ELSE ISNULL(a.FirstName,'') + replace( (  ' ' + ISNULL(a.MiddleName+' ',' '),'  ',' ') + ISNULL(a.LastName,'')
END AS 'CustomerName'