Sql 是否有方法根据R中的一组条件,使用表T2中的B列更新表T1中的a列?
我试图在R中创建一个类似于以下内容的代码:Sql 是否有方法根据R中的一组条件,使用表T2中的B列更新表T1中的a列?,sql,r,dataframe,dplyr,data.table,Sql,R,Dataframe,Dplyr,Data.table,我试图在R中创建一个类似于以下内容的代码: UPDATE Table_1 A SET Column_1= (SELECT Column_2 FROM Tabla_2 WHERE Column_3=A.Column_3 AND Column_4=A.Column_4 HAVING INDEX=MIN(INDEX)); 例如,具有以下数据帧: Table_1 <-data.frame( Column_1=c(1,1,1,1), Column_3=c("1","2","3","1"
UPDATE Table_1 A SET Column_1=
(SELECT Column_2 FROM Tabla_2 WHERE
Column_3=A.Column_3 AND
Column_4=A.Column_4
HAVING INDEX=MIN(INDEX));
例如,具有以下数据帧:
Table_1 <-data.frame(
Column_1=c(1,1,1,1),
Column_3=c("1","2","3","1"),
Column_4=c("A","B","C","A")
)
Table_2<-data.frame(
Column_2 =c(2,3,4,5),
Column_3=c("1","2","3","4"),
Column_4=c("A","B","C","D")
)
Table_1使用数据。Table
,我们可以进行连接和分配(:=
)
使用data.table
,我们可以进行连接和分配(:=
)
我只是添加了一个可复制的示例我只是添加了一个可复制的示例
Table_1 <-data.frame(
Column_1=c(2,3,4,2),
Column_3=c("1","2","3","1"),
Column_4=c("A","B","C","A")
)
library(data.table)
setDT(Table_1)[Table_2, Column_1 := Column_2, on = .(Column_4)]
Table_1
# Column_1 Column_3 Column_4
#1: 2 1 A
#2: 3 2 B
#3: 4 3 C
#4: 2 1 A