Question

在R中 - 是否可以使用IN进行mysql查询，其中IN中的值来自DataFrame列？

我尝试做的事情的例子：

Directory = read.csv("worlddirectory.csv", header = TRUE, sep = ",",stringsAsFactors=FALSE)

Active_Customers = Directory[(Directory$Status == "Active"),]

PhoneNumbers = dbGetQuery(DBConnection,
"
Select
db.phonenumbers,
db.names
from
database db
where
db.country IN
(
Active_Customers$Country
);"

Answer 1

我们可以看到here，预期语句如下：

WHERE column_name IN (value1, value2, ...);

我们可以将paste与参数collapse=", "一起使用以获得所需的格式。我认为这应该有效：

PhoneNumbers = dbGetQuery(DBConnection,
paste0("SELECT db.phonenumbers, db.names ",
"FROM database db ",
"WHERE db.country IN (",
       paste(Active_Customers$Country,collapse=", "),");"))

示例：

Active_Customers <- data.frame(Country=c("NL","BE","US"))

paste0("SELECT db.phonenumbers, db.names ",
"FROM database db ",
"WHERE db.country IN (",
paste(Active_Customers$Country,collapse=", "),");")

输出：

[1] "SELECT db.phonenumbers, db.names FROM database db WHERE db.country IN (NL, BE, US);"

希望这有帮助！

R - R中mysql查询内的数据帧值

1 个答案: