How to use CASE to get 3 columns from a single column?

问题

I have one table "DataDollar"...and 2 columns "LineNmbr" & "DollarAmt" in that.

I need to display this column values as in three columns depending upon their values.

Please help me !

SELECT
 DollarAmt AS
 CASE LineNmbr
    WHEN 19
        THEN  'A-Amt'
    WHEN 20
        THEN   'P-Amt'
    ELSE
          'D-Amt'
  END        
 FROM DataDollar

回答1:

Try using three case expressions, one for each column in the result set:

SELECT
    CASE LineNumber WHEN 19 THEN DollarAmt END AS AAmt,
    CASE LineNumber WHEN 20 THEN DollarAmt END AS PAmt,
    CASE WHEN LineNumber <> 19 AND LineNumber <> 20
        THEN DAmt
    END AS DAmt
FROM DataDollar

回答2:

select 
  case LineNmbr when 19 then DollarAmt else null end as 'A-Amt',  
  case LineNmbr when 20 then DollarAmt else null end as 'P-Amt',
  case when (LineNmbr <> 19) and (LineNmbr <> 20) then DollarAmt else null end as 'D-Amt'
from DataDollar    

来源：https://stackoverflow.com/questions/5159869/how-to-use-case-to-get-3-columns-from-a-single-column