SQL查詢變量

Question

我有一個SQL查詢，可獲取特定股票的交易數據。 我現在嘗試遍歷不同的股票以應用特定的分析。 下面的代碼顯示了我在循環中將變量傳遞給查詢以及“硬編碼”查詢的嘗試。

任何指導將不勝感激。

my.stocks <- c('ABL','IPL')

for (i in 1:2)
{
channel <- odbcConnect("Public_Trades")
my.frame1 <- sqlQuery(channel,
"SELECT TRADE_DATE_TIME,
 PRICE,
 QUANTITY
 FROM [ISLDWODS].[HERMES_PUBLIC].[PUBLIC_TRADES_HISTORY]
 where TRADE_DATE_TIME > '2012-11-01' and TRADE_TYPE ='AT' and INSTR_CODE = " & my.stocks[i] &  
 "order by TRADE_DATE_TIME asc")

my.frame2 <- sqlQuery(channel,
"SELECT TRADE_DATE_TIME,
 PRICE,
 QUANTITY
 FROM [ISLDWODS].[HERMES_PUBLIC].[PUBLIC_TRADES_HISTORY]
 where TRADE_DATE_TIME > '2012-11-01' and TRADE_TYPE in ('AT','UT') and INSTR_CODE = 'MPC'  
 order by TRADE_DATE_TIME asc")


close(channel)
}

Answer 1

謝謝sgibb，

粘貼解決了這個問題：

my.stocks <- c("'ABL'","'IPL'")


for (i in 1:2)
{

my.string1 <- paste("SELECT TRADE_DATE_TIME,PRICE,QUANTITY  
              FROM [ISLDWODS].[HERMES_PUBLIC].[PUBLIC_TRADES_HISTORY] 
              where TRADE_DATE_TIME > '2012-11-01' and TRADE_TYPE ='AT' and INSTR_CODE = ", my.stocks[1]," order by TRADE_DATE_TIME asc")

my.string2 <- paste("SELECT TRADE_DATE_TIME,PRICE,QUANTITY  
              FROM [ISLDWODS].[HERMES_PUBLIC].[PUBLIC_TRADES_HISTORY] 
              where TRADE_DATE_TIME > '2012-11-01' and TRADE_TYPE in ('AT','UT') and INSTR_CODE = ", my.stocks[1]," order by TRADE_DATE_TIME asc")

channel <- odbcConnect("Public_Trades")
my.frame1 <- sqlQuery(channel,my.string1)

my.frame2 <- sqlQuery(channel,my.string2)
}