AlterQuery  t1 (children 2)
 ExpressionList (children 1)
  AlterCommand ADD_COLUMN (children 1)
   ColumnDeclaration s3 (children 2)
    DataType String
    Function concat (children 1)
     ExpressionList (children 3)
      Identifier s2
      Literal \'_\'
      Identifier s1
 Identifier t1