在 R 脚本中传递字符串变量以在 SQL 语句中使用它 [英] Pass string variable in R script to use it in SQL statement
问题描述
我尝试在 R 脚本中使用字符串变量通过 SQL 语句使用,例如:
I tried use a string variable in R script to use through SQL statement for example:
x="PASS"
SQL<- paste("select ID, NAME, STATUS from STUDENT where STATUS =(",x,")",sep="")
Q1 <- dbGetQuery(con, SQL)
错误说:
mysqlExecStatement(conn, statement, ...) 中的错误:
RS-DBI 驱动程序:(无法运行语句:'where 子句'中的未知列'PASS')
Error in mysqlExecStatement(conn, statement, ...) :
RS-DBI driver: (could not run statement: Unknown column 'PASS' in 'where clause')
这意味着 STATUS =(",x,")" = PASS 并且它必须'PASS'并加上引号''
That means STATUS =(",x,")" = PASS and it must 'PASS' with add quote ''
我尝试将 ''
放在下面,但没有成功.
I tried to put the ''
but no success as the following.
SQL <- paste("select ID, NAME, STATUS from STUDENT where STATUS ='(",x,")' ",sep="")
Q1 <- dbGetQuery(con, SQL)
我用数字对其进行了测试,它运行良好,但是当我使用字符串时,它不起作用,因为该值必须在引号 ' '
中.
I tested it with number and it is work well but when I use string it is not working, because the value must be in quotes ' '
.
推荐答案
使用 sprintf
代替:
x <- "PASS"
sprintf("select ID, NAME, STATUS from STUDENT where STATUS = '%s'", x)
## [1] "select ID, NAME, STATUS from STUDENT where STATUS = 'PASS'"
这篇关于在 R 脚本中传递字符串变量以在 SQL 语句中使用它的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!