RMySQL dbWriteTable与field.types [英] RMySQL dbWriteTable with field.types

问题描述

我有一个名为df的数据框，看起来像这样:

I have a data frame, called df, that looks like this:

dte, val
2012-01-01, 23.2323
2012-01-02, 34.343

列上的类型是日期和数字.我想使用已经打开的连接将其写入MySQL数据库.连接正常，因为我可以查询数据库.我尝试运行以下命令:

The type on the columns is date and numeric. I would like to write this to a MySQL database using an already open connection. The connection works fine as I am able to query the db fine. I try to run the following:

dbWriteTable(con, name="table_name", value=df, field.types=list("date", "double(20,10)"))

这会产生错误:

函数(类，fdef，mtable)中的错误:无法找到函数"make.db.names"，签名"MySQLConnection"，"NULL"的继承方法

Error in function (classes, fdef, mtable) : unable to find an inherited method for function "make.db.names", for signature "MySQLConnection", "NULL"

如果我未指定field.types，则运行:

If I do not specify a field.types, and run:

dbWriteTable(con, name="table_name", value=df)

我得到了错误:

mysqlExecStatement(conn，statement，...)中的错误:RS-DBI驱动程序:(无法运行语句:密钥规范中使用的BLOB/TEXT列'dte'没有密钥长度)

Error in mysqlExecStatement(conn, statement, ...) : RS-DBI driver: (could not run statement: BLOB/TEXT column 'dte' used in key specification without a key length)

任何人都可以对此有所了解吗?

Can anyone shed some light on this?

谢谢

推荐答案

玩了之后，我意识到了问题所在:field.types必须是一个命名的 list 向量，而不仅仅是一个列表;此外，不得包含行名，否则我们需要三种字段类型.对于上面的示例，以下工作正常:

After playing with things, I realized what the problem is: field.types must be a NAMED list vector, not simply a list; additionally the row names must not be included otherwise we need three field types. For the above example, the following works fine:

dbWriteTable(con, name="table_name", value=df,
  field.types = c(dte="date", val="double(20,10)"), row.names=FALSE)

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