CreateQuery test_a (children 3)
 Identifier test_a
 Columns definition (children 1)
  ExpressionList (children 3)
   ColumnDeclaration OldColumn (children 2)
    DataType String
    Literal \'\'
   ColumnDeclaration EventDate (children 2)
    DataType Date
    Function toDate (children 1)
     ExpressionList (children 1)
      Identifier EventTime
   ColumnDeclaration EventTime (children 1)
    DataType DateTime
 Storage definition (children 1)
  Function MergeTree (children 1)
   ExpressionList (children 3)
    Identifier EventDate
    Identifier EventTime
    Literal UInt64_8192