这看起来很荒谬,但我就是无法做到这一点 - 任何帮助都非常感谢!
基本上:我正在使用 RMySQL 执行一些简单的 SQL,以便了解 SQL 的工作原理。select
作为一个简单的示例,我想将几个 SQL 查询链接在一起。这在 RMySQL PDF 中有介绍 - 但其中的示例似乎是不正确的语法(http://cran.r-project.org/web/packages/RMySQL/RMySQL.pdf,第 3 页,示例 6)。
如果我有三个查询,请这样说:
q1 <- "SELECT db.table FROM table WHERE stuff = 'blah' "
q2 <- "SELECT db.other_table FROM other_table WHERE stuff = 'different blah' "
q3 <- "SELECT db.table2 FROM table2 WHERE table2 = 1000"
并尝试paste
如下:
script <- paste(q1, q2, q3, sep=";")
结果是
> script
[1] "SELECT db.table FROM table WHERE stuff = 'blah' ;SELECT fb.other_table FROM
other_table WHERE stuff = 'different blah' ;SELECT db.table2 FROM table2 WHERE table2 =
'1000'
所以调用dbSendQuery
显然失败了。
我试过\"
了,但这也不起作用:
q1 <- "SELECT db.table FROM table WHERE stuff = 'blah' \" "
q2 <- "SELECT db.other_table FROM other_table WHERE stuff = 'different blah' \""
q3 <- "SELECT db.table2 FROM table2 WHERE table2 = 1000 \" "
script <- paste(q1, q2, q3, sep=";")
> script
[1] "SELECT db.table FROM table WHERE stuff = 'blah' \" ; ;SELECT db.other_table FROM
other_table WHERE stuff = 'different blah' \";SELECT db.table2 FROM table2 WHERE table2
= 1000 \" "
谁能指出我做错了什么?
编辑:只是为了澄清,通过 RMySQL 执行如下:
my.queries <- dbGetQuery(my.con, script, client.flag = CLIENT_MULTI_STATEMENTS)
根据 RMySQL 手册,我得到
RS-DBI driver: (could not run statement: You have an error in your SQL syntax;
据推测,这是因为paste
函数的结果应该是:
"SELECT db.table FROM table WHERE stuff = 'blah'" ;"SELECT fb.other_table FROM
other_table WHERE stuff = 'different blah'" ;"SELECT db.table2 FROM table2 WHERE table2
= '1000'"
每个单独的查询都工作得很好,所以我假设是我的paste
命令导致了这个问题。
编辑:为了简化这一点:假设我有两个字符串,如下所示:
t1 <- "the 'stuff'"
t2 <- "more 'stuff'"
paste(t1, t2, sep=";")
[1] "the 'stuff' ; more 'stuff' "
我想要的是粘贴命令的结果是"the 'stuff'";"more 'stuff'"
.