很简单- sql 返回dataframe，但您确定它只有一个元素，因此可以执行以下操作：

val last_max_date_from_hive = hivecontext.sql("select min(SampleTime) max_SampleTime from mytable")

val firstRow = last_max_date_from_hive.map {
    // only value is important
    case Row (value) => value.asInstanceOf[java.sql.Timestamp]; // cast to Date
}.first()

// we use SimpleDateFormat to parse to proper string format
val df2 = sqlContext.sql ("select * from mytable where SampleTime > cast('" 
    + new java.text.SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS").format(firstRow) 
    + "' as date)");

如果不想解析timestamp对象，那么可以使用 from_unixtime 功能和 getTime() :

val firstRow = las_max_date_from_hive.map {
    case Row (value) => value.asInstanceOf[java.sql.Timestamp].getTime() / 1000
}.first();

val df2 = sqlContext.sql ("select * from mytable where cast(SampleTime as timestamp) > from_unixtime(" + firstRow + ")")