CreateQuery null_in_subquery (children 3)
 Identifier null_in_subquery
 Columns definition (children 1)
  ExpressionList (children 3)
   ColumnDeclaration dt (children 1)
    DataType DateTime
   ColumnDeclaration idx (children 1)
    DataType int
   ColumnDeclaration i (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType UInt64
 Storage definition (children 4)
  Function MergeTree (children 1)
   ExpressionList
  Identifier dt
  Identifier idx
  Set
