title: Can't access existing MonetDB with dplyr
body: <p>I created a MonetDBLite database yesterday, populated it, and was accessing it with <code>dplyr</code>, however this morning I don't seem able to use <code>dplyr</code>.</p>
  
  <p>Here's my connection:</p>
  
  <pre><code>statcast_db &lt;- MonetDBLite::src_monetdblite("/Users/williampetti/statcast_database/statcast_db_Monet", create = FALSE)
  </code></pre>
  
  <p>And here's a simple query for the <code>statcast_17</code> table:</p>
  
  <pre><code>statcast_db %&gt;% 
      tbl("statcast_17") %&gt;% 
      select(game_date) %&gt;% 
      distinct() %&gt;% 
      collect() %&gt;% 
      tail(n = 1)
  </code></pre>
  
  <p>Yesterday, this worked fine. This morning, I get this error:</p>
  
  <pre><code>Error in UseMethod("db_query_fields") : 
    no applicable method for 'db_query_fields' applied to an object of class "MonetDBEmbeddedConnection"
  </code></pre>
  
  <p>If I use a simple <code>dbGetQuery</code> call, however, it works fine:</p>
  
  <pre><code>&gt; dbGetQuery(statcast_db$con, "SELECT game_date FROM statcast_17 ORDER BY game_date DESC LIMIT 1")
     game_date
  1 2017-04-29
  </code></pre>
  
  <p>Here's my session info:</p>
  
  <pre><code>&gt; sessionInfo()
  R version 3.3.1 (2016-06-21)
  Platform: x86_64-apple-darwin13.4.0 (64-bit)
  Running under: OS X 10.11.6 (El Capitan)
  
  locale:
  [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  other attached packages:
   [1] xml2_1.1.1        baseballr_0.3.1   RSQLite_1.0.0     pacman_0.4.1     
   [5] dplyr_0.5.0       purrr_0.2.2       readr_1.0.0       tidyr_0.6.0      
   [9] tibble_1.2        ggplot2_2.2.1     tidyverse_1.0.0   magrittr_1.5     
  [13] MonetDBLite_0.3.1 RMySQL_0.10.9     DBI_0.5-1        
  
  loaded via a namespace (and not attached):
   [1] splines_3.3.1       lattice_0.20-33     colorspace_1.2-6   
   [4] htmltools_0.3.5     mgcv_1.8-12         chron_2.3-47       
   [7] XML_3.98-1.6        survival_2.40-1     hexbin_1.27.1      
  [10] foreign_0.8-66      RColorBrewer_1.1-2  plyr_1.8.4         
  [13] stringr_1.2.0       munsell_0.4.3       gtable_0.2.0       
  [16] rvest_0.3.2         XML2R_0.0.6         codetools_0.2-14   
  [19] latticeExtra_0.6-28 knitr_1.14          reldist_1.6-6      
  [22] htmlTable_1.7       Rcpp_0.12.9         acepack_1.4.1      
  [25] scales_0.4.1        pitchRx_1.8.2       Hmisc_4.0-0        
  [28] gridExtra_2.2.1     digest_0.6.11       stringi_1.1.3      
  [31] grid_3.3.1          tools_3.3.1         bitops_1.0-6       
  [34] lazyeval_0.2.0      RCurl_1.95-4.8      Formula_1.2-1      
  [37] cluster_2.0.4       MASS_7.3-45         Matrix_1.2-6       
  [40] data.table_1.9.6    lubridate_1.6.0     httr_1.2.1         
  [43] assertthat_0.1      R6_2.1.3            rpart_4.1-10       
  [46] nnet_7.3-12         nlme_3.1-128   
  </code></pre>