Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
274 views
in Technique[技术] by (71.8m points)

sql - Dynamic "string" in R

Simple question, but cannot find the answer.

Instead of:

Df <- sqlQuery(ch, "SELECT * FROM tblTest WHERE Id=25")

I want a more dynamic piece of code. Something like:

Id <- 25
Df <- sqlQuery(ch, c("SELECT * FROM tblTest WHERE Id=", Id))

But this is not correct.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

We can use paste:

Df <- sqlQuery(ch, paste("SELECT * FROM tblTest WHERE Id =", Id))

c concatenates into a vector, paste is for string concatenation.

Or we can use sprintf:

sprintf("SELECT * FROM tblTest WHERE Id = %s", Id)

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...