Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 6)
     Identifier ts
     Identifier id
     Identifier id_b
     Identifier b.ts
     Identifier b.id
     Identifier id_c
    TablesInSelectQuery (children 2)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Subquery (alias a) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 2)
           ExpressionList (children 3)
            Identifier ts
            Identifier id
            Identifier id_b
           TablesInSelectQuery (children 1)
            TablesInSelectQueryElement (children 1)
             TableExpression (children 1)
              TableIdentifier A
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       TableIdentifier B (alias b)
      TableJoin (children 1)
       Function equals (children 1)
        ExpressionList (children 2)
         Identifier b.id
         Identifier a.id_b
    Function lessOrEquals (children 1)
     ExpressionList (children 2)
      Identifier a.ts
      Function toDateTime (children 1)
       ExpressionList (children 1)
        Literal \'1970-01-01 03:00:00\'