R连接mysql时，已列出所有表，错误Error in odbcTableExists(channel, sqtable) object 'wuliudata' not found解决方案

> library(RODBC)
> myconn <- odbcConnect("mysql_data",uid="wenrui",pwd="wenrui")
> myconn
RODBC Connection 1
Details:
case=tolower
DSN=mysql_data
UID=wenrui
PWD=******

> sqlTables(myconn)
TABLE_CAT TABLE_SCHEM          TABLE_NAME TABLE_TYPE REMARKS
1     wuliu                       wuliudata      TABLE
2     wuliu                      wuliudata2      TABLE
3     wuliu                    wuliudatanew      TABLE
4     wuliu                   wuliudatanew2      TABLE
5     wuliu                   wuliudatanew3      TABLE
6     wuliu                  wuliudataonly2      TABLE
7     wuliu             wuliudataonly2_copy      TABLE
8     wuliu                       wuliunew3      TABLE

> wuliudata <- sqlFetch(myconn,wuliunew3)
Error in odbcTableExists(channel, sqtable) : object 'wuliunew3' not found

> wuliudata <- sqlFetch(myconn,"wuliunew3")