title: Check every column in a spark dataframe has a certain value
body: <p>Can we check to see if every column in a spark dataframe contains a certain string(example "Y") using Spark-SQL or scala?</p>
  
  <p>I have tried the following but don't think it is working properly.</p>
  
  <pre><code>df.select(df.col("*")).filter("'*' =='Y'")
  </code></pre>
  
  <p>Thanks,
  Sai</p>