title: Bigquery SQL: convert array to columns
body: <p>I have a table with a field A where each entry is a fixed length array A of integers (say length=1000). I want to know how to convert it into 1000 columns, with column name given by index_i, for i=0,1,2,...,999, and each element is the corresponding integer. I can have it done by something like</p>
  <pre><code>   A[OFFSET(0)] as index_0,
     A[OFFSET(1)] as index_1
     A[OFFSET(2)] as index_2,
     A[OFFSET(3)] as index_3,
     A[OFFSET(4)] as index_4,
      ...
     A[OFFSET(999)] as index_999,
  </code></pre>
  <p>I want to know what would be an elegant way of doing this. thanks!</p>