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我有這個疑問轉換字符類Date
sql <- "select
observationid::text,id,date, ST_X(location::geometry) as lon, ST_Y(location::geometry) as lat
from test
where date>= '1850-01-01' and date <'1851-01-01'"
datain<-dbGetQuery(dbh,sql)
,我從R.運行,我想什麼做的是設置日期範圍的東西查詢外像
datamin <- '1850-01-01'
datamax <- '1851-01-01'
sql <- "select
observationid::text,id,date, ST_X(location::geometry) as lon, ST_Y(location::geometry) as lat
from test
where date>= datamin and date <datamax"
datain<-dbGetQuery(dbh,sql)
但我得到這個錯誤
Error in postgresqlExecStatement(conn, statement, ...) :
RS-DBI driver: (could not Retrieve the result : ERROR: column "datamin" does not exist
非常感謝
R不解釋裏面像其他一些編程語言的字符串變量。你需要用'paste'來構造你的查詢字符串:'sql < - paste(「select blah blah where date> =」,datamin,「and ...」)'。你應該閱讀一些[介紹R手冊](http://cran.r-project.org/doc/manuals/R-intro.pdf) – BrodieG
對不起,但我沒有工作(因爲選擇?) – user3036416
打印'sql' var並查看它是否包含您認爲應該的內容。 – BrodieG