CreateQuery data_null (children 3)
 Identifier data_null
 Columns definition (children 1)
  ExpressionList (children 4)
   ColumnDeclaration a (children 1)
    DataType INT
   ColumnDeclaration b (children 1)
    DataType INT
   ColumnDeclaration c (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType INT
   ColumnDeclaration d (children 1)
    DataType INT
 Storage definition (children 1)
  Function Memory (children 1)
   ExpressionList