[root@centos00 ~]$ cd /opt/cdh5.14.2/hadoop-2.6.0-cdh5.14.2/
[root@centos00 hadoop-2.6.0-cdh5.14.2]$ sbin/hadoop-daemon.sh start namenode
[root@centos00 hadoop-2.6.0-cdh5.14.2]$ sbin/hadoop-daemon.sh start datanode
[root@centos00 ~]$ cd /opt/cdh5.14.2/hive-1.1.0-cdh5.14.2/
[root@centos00 hive-1.1.0-cdh5.14.2]$ bin/hive --service metastore &
[root@centos00 hadoop-2.6.0-cdh5.14.2]$ cd ../spark-2.2.1-cdh5.14.2/
[root@centos00 spark-2.2.1-cdh5.14.2]$ sbin/start-master.sh
[root@centos00 spark-2.2.1-cdh5.14.2]$ sbin/start-slaves.sh
[root@centos00 spark-2.2.1-cdh5.14.2]$ bin/spark-shell --master local[2]
// 获取当前日期
scala> spark.sql("select current_date").show
+--------------+
|current_date()|
+--------------+
| 2020-08-17|
+--------------+
// 获取当前时间
scala> spark.sql("select current_timestamp").show
+--------------------+
| current_timestamp()|
+--------------------+
|2020-08-17 23:46:...|
+--------------------+
// 获取当前时间
scala> spark.sql("select now()").show
+--------------------+
| current_timestamp()|
+--------------------+
|2020-08-17 23:46:...|
+--------------------+
// 指定日期转化为时间戳
scala> spark.sql("SELECT to_unix_timestamp('2020-08-17', 'yyyy-MM-dd')").show
+-----------------------------------------+
|to_unix_timestamp(2020-08-17, yyyy-MM-dd)|
+-----------------------------------------+
| 1597590000|
+-----------------------------------------+
// 当前日期转化为时间戳
scala> spark.sql("SELECT to_unix_timestamp(current_timestamp, 'yyyy-MM-dd')").show
+--------------------------------------------------+
|to_unix_timestamp(current_timestamp(), yyyy-MM-dd)|
+--------------------------------------------------+
| 1597675747|
+--------------------------------------------------+
// 获取昨天的日期
scala> spark.sql("SELECT date_sub(current_date, 1)").show
+---------------------------+
|date_sub(current_date(), 1)|
+---------------------------+
| 2020-08-16|
+---------------------------+
// 获取当前结束日期和开始日期的差值
scala> spark.sql("SELECT datediff('2020-08-18', '2020-08-16')").show
+------------------------------------------------------------+
|datediff(CAST(2020-08-18 AS DATE), CAST(2020-08-16 AS DATE))|
+------------------------------------------------------------+
| 2|
+------------------------------------------------------------+
