RODBC字符串被截断 [英] RODBC string getting truncated

问题描述

我正在使用RODBC将数据从MySql Server提取到R中.
因此，在数据库的一列中是一个字符向量

I am fetching data from MySql Server into R using RODBC.
So in one column of the database is a character vector

SELECT MAX(CHAR_LENGTH(column)) FROM reqtable;

返回26566

现在，我将向您展示一个示例，说明我是如何遇到问题的

Now I will show you an example how I am running into the problem

`library(RODBC)
 con <- odbcConnect("mysqlcon")
 rslts <- as.numeric(sqlQuery(con,
                          "SELECT CHAR_LENGTH(column) FROM reqtable LIMIT 10",
                          as.is=TRUE)[,1])

` 返回

> rslts
 [1]  62  31  17 103  30 741  28  73  25 357

其中 rslts <- nchar(as.character(sqlQuery(con, "SELECT column FROM reqtable LIMIT 10", as.is=TRUE)[,1])) 返回

where as rslts <- nchar(as.character(sqlQuery(con, "SELECT column FROM reqtable LIMIT 10", as.is=TRUE)[,1])) returns

> rslts
 [1]  62  31  17 103  30 255  28  73  25 255

所以长度大于255的字符串将在255处被截断.有没有办法我可以获取完整的字符串.

So strings with length > 255 is getting truncated at 255. Is there a way I can get the full string.

谢谢

推荐答案

PostgreSQL ODBC驱动程序有一个名为MaxLongVarcharSize的变量，我发现默认情况下将其设置为8190(我在Windows和Ubuntu上都使用过). MySQL ODBC驱动程序可能将类似的变量设置为255.

The PostgreSQL ODBC driver has a variable called MaxLongVarcharSize that I have found set to 8190 by default (I've used it both on Windows and Ubuntu). It is possible that the MySQL ODBC driver has a similar variable set to 255.

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