title: Dropping containing NA rows with dbplyr
body: <p>here is how I ran some SQL queries by dbplyr</p>
  <pre><code>library(tidyverse)
  library(dbplyr)
  library(DBI)
  library(RPostgres)
  library(bit64)
  library(tidyr)
  
  drv &lt;- dbDriver('Postgres')
  
  con &lt;- dbConnect(drv,dbname='mydb',port=5432,user='postgres')
  
  table1 &lt;- tbl(con,'table1')
  table2 &lt;- tbl(con,'table2')
  table3 &lt;- tbl(con,'table3')
  
  table1 %&gt;% mutate(year=as.integer64(year)) %&gt;% left_join(table2,by=c('id'='id')) %&gt;%
  left_join(table3,by=c('year'='year'))
  </code></pre>
  <p>I wanna drop some rows which include NA then <code>collect</code> my final table but couldn't find anything helpful works with dbplyr queries.</p>
  <p>I tried to pipe <code>drop_na()</code> from <code>tidyr</code> and some other base functions (<code>complete.cases()</code> etc.). Would you suggest me anything to succeed my aim ? Piping an SQL query (like <code>WHERE FOO IS NOT NULL</code>) to dbplyr query is also welcome.</p>
  <p>Thanks in advance.</p>