title: How to query multiple nested fields in Bigquery?
body: <p>When i query two level nested field i miss some rows. </p>
  
  <p>The schema is like this:</p>
  
  <pre><code>Productid   STRING  REQUIRED 
  Variants    RECORD  REPEATED
  Variants.SKU    STRING  NULLABLE
  Variants.Size   STRING  NULLABLE
  Variants.Prices RECORD  REPEATED
  Variants.Prices.Country STRING  NULLABLE
  Variants.Prices.Currency    STRING  NULLABLE
  </code></pre>
  
  <p>Some of Variants.Prices records are empty.</p>
  
  <p>When i query this table with this query:</p>
  
  <pre><code>select Productid,Variants.SKU,Variants.Size
  from ga-export-0000.feed.feed_dev
  ,UNNEST (Variants) AS Variants
  </code></pre>
  
  <p>i get many more rows than with this one:</p>
  
  <pre><code>select Productid,Variants.SKU,Variants.Size
  ,Prices.Currency,Prices.Country
  from ga-export-0000.feed.feed_dev
  ,UNNEST (Variants) AS Variants
  ,UNNEST(Variants.Prices) as Prices 
  </code></pre>
  
  <p>That's because it doesn't returns rows with missing Variants.Prices.</p>
  
  <p>How can i modify my second query so it returns all the rows and if Variants.Prices is missing it shows NULL? </p>