連接表和使用子查詢時的未知列

Question

我使用以下stackoverflow帖子嘗試獲取具有最新日期的記錄： 從表中選擇信息，其中行具有最大日期

我寫了以下查詢：

SELECT AR_SQ.SYMBOL, AR_SQ.NAME, AR_SQ.LAST, FF_PS.SECTOR, FF_PS.SECTOR_TAGS, HP.LAST_10_DAYS, HP.YTD_PERF 
FROM AR_STOCK_QUOTE AR_SQ 
LEFT JOIN (
SELECT HP.SYMBOL, max(TRADE_DATE) as MaxDate 
FROM FF_HISTORICAL_STOCK_PRICE HP
GROUP BY HP.SYMBOL
) 
HP on HP.SYMBOL = AR_SQ.SYMBOL 
JOIN FF_PRIMARY_STOCK_TABLE FF_PS on FF_PS.SYMBOL = AR_SQ.SYMBOL

但是，當我這樣做時，我收到一條錯誤消息，內容如下：

錯誤代碼：1054。“字段列表”中的未知列“ HP.LAST_10_DAYS”

為什么會這樣，因為已經定義了HP並且它是該表中的一個字段？

Answer 1

因為您要對選擇語句（而不是表“ FF_HISTORICAL_STOCK_PRICE”）進行聯接，所以無法在全局選擇上使用HP，因為未在其中定義HP

SELECT AR_SQ.SYMBOL, AR_SQ.NAME, AR_SQ.LAST, FF_PS.SECTOR, FF_PS.SECTOR_TAGS, HP.LAST_10_DAYS, HP.YTD_PERF  #3- you cannot use HP here
FROM AR_STOCK_QUOTE AR_SQ 
LEFT JOIN (
# 1- you are not doing ajoin on the table FF_HISTORICAL_STOCK_PRICE HP
# 2- you can use HP on this select 
SELECT HP.SYMBOL, max(TRADE_DATE) as MaxDate 
FROM FF_HISTORICAL_STOCK_PRICE HP
GROUP BY HP.SYMBOL
) 
HP on HP.SYMBOL = AR_SQ.SYMBOL 
JOIN FF_PRIMARY_STOCK_TABLE FF_PS on FF_PS.SYMBOL = AR_SQ.SYMBOLenter code here

將字段添加到連接部分的select語句中，現在它們將存在於結果HP中，並嘗試對select使用不同的別名

SELECT AR_SQ.SYMBOL, AR_SQ.NAME, AR_SQ.LAST, FF_PS.SECTOR, FF_PS.SECTOR_TAGS, RS.LAST_10_DAYS, RS.YTD_PERF 
FROM AR_STOCK_QUOTE AR_SQ 
LEFT JOIN (
# add the last_10_days to the fields of you select statement now you can select them
SELECT HP.SYMBOL, max(TRADE_DATE) as MaxDate ,HP.LAST_10_DAYS, HP.YTD_PERF 
FROM FF_HISTORICAL_STOCK_PRICE HP
GROUP BY HP.SYMBOL
) RS on RS.SYMBOL = AR_SQ.SYMBOL  #HP is a result of select statement 
JOIN FF_PRIMARY_STOCK_TABLE FF_PS on FF_PS.SYMBOL = AR_SQ.SYMBOL