SQL Pivot 在 varchar 列上

Question

我有一個看起來像這樣的結果集：

FlightCode  col2    Col3    SourceAirportCode
Flight007   NYC     SOURCE      64
Flight008   ORD     TARGET      87
Flight007   SEA     TARGET      NULL
Flight008   PHX     SOURCE      NULL

我試圖達到的最終結果是：

FlightCode  Source  Target  SourceAirportCode
Flight007   NYC     SEA     64
Fight008    PHX     ORD     87

這是 pivot 問題嗎？ 我嘗試了一些旋轉但沒有運氣，或者我只是對 Pivot 了解不夠。這是

SQL 小提琴演示

使用架構和插入語句。 請指教。

Answer 1

假設航班代碼實際匹配，則使用條件聚合：

select flightcode,
       max(case when col3 = 'SOURCE' then col2 end) as source,
       max(case when col3 = 'TARGET' then col2 end) as target,
       max(SourceAirportCode) as SourceAirportCode
from t
group by flightcode;

Answer 2

您可以使用自聯接並將一個表視為源，將另一個表視為目標。

WITH flight(FlightCode,  col2,    Col3,    SourceAirportCode)
AS 
(
 SELECT 'Flight007','NYC','SOURCE',64   UNION
 SELECT 'Flight008','ORD','TARGET',87   UNION
 SELECT 'Flight007','SEA','TARGET',NULL UNION
 SELECT 'Flight008','PHX','SOURCE',NULL
)

SELECT f.FlightCode, s.col2 as 'SOURCE', t.col2 as 'TARGET',
       f.SourceAirportCode
FROM flight f
JOIN flight s ON s.Col3 = 'SOURCE' AND s.FlightCode = f.FlightCode
JOIN flight t ON t.Col3 = 'TARGET' AND t.FlightCode = f.FlightCode
WHERE f.SourceAirportCode IS NOT NULL


FlightCode  SOURCE  TARGET  SourceAirportCode
 Flight007  NYC      SEA    64
 Flight008  PHX      ORD    87