三、从hdfs导出到MySQL
清空表
mysql> delete from test;
Query OK, 2 rows affected (0.00 sec)
mysql> select * from test;
Empty set (0.00 sec)
导出
[zhouhh@Hadoop48 ~]$ sqoop-export --connect jdbc:mysql://192.168.10.48:3306/toplists --username root --table test --export-dir test
Note: /tmp/sqoop-zhouhh/compile/7adaaa7ffe5f49ed9d794b1be8a9a983/test.Java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
导出时，–connect,–table, –export-dir是必须设置的。其中toplists是库名，–table是该库下的表名。 –export-dir是要导出的HDFS平面文件位置。如果不是绝对路径，指/user/username/datadir
检查mysql表
mysql> select * from test;
+----+--------+---------+------------+---------+---------+
| id | name | price | cdate | version | comment |
+----+--------+---------+------------+---------+---------+
| 1 | iphone | 3900.00 | 2012-07-18 | 1 | 8g |
| 2 | ipad | 3200.00 | 2012-07-16 | 2 | 16g |
+----+--------+---------+------------+---------+---------+
2 rows in set (0.00 sec)
可见导出成功。
四、不执行mapreduce，但生成导入代码
[zhouhh@Hadoop48 ~]$ sqoop codegen --connect jdbc:mysql://192.168.10.48:3306/toplists --username root --table test --class-name Mycodegen
Note: /tmp/sqoop-zhouhh/compile/104b871487669b89dcd5b9b2c61f905f/Mycodegen.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
[zhouhh@Hadoop48 ~]$ sqoop help codegen
usage: sqoop codegen [GENERIC-ARGS] [TOOL-ARGS]
sqoop导入时，可以加选择语句，以过滤和综合多表，用–query.也可以只加条件，用–where。这样可以不必每次导入整张表。 如 –where ‘id > 1000′
示例，采用join选择多表数据：
sqoop import –query ‘select a.*,b.* from a join b on (a.id == b.id) where $conditions’ -m 1 –target-dir /usr/foo/joinresults