[root@172 ~]# su hadoop
[hadoop@172 ~]# cd /usr/local/service/sqoop

[hadoop@172 sqoop]$ mysql -h $mysqlIP –p
Enter password:

mysql> use test;
Database changed

mysql> create table sqoop_test(id int not null primary key auto_increment, title varchar(64), time timestamp, content varchar(255));
Query ok , 0 rows affected(0.00 sec)

mysql> insert into sqoop_test values(null, 'first', now(), 'hdfs');
Query ok, 1 row affected(0.00 sec)

mysql> insert into sqoop_test values(null, 'second', now(), 'mr');
Query ok, 1 row affected (0.00 sec)

mysql> insert into sqoop_test values(null, 'third', now(), 'yarn');
Query ok, 1 row affected(0.00 sec)

Mysql> select * from sqoop_test;
+----+--------+---------------------+---------+
| id | title  | time                | content |
+----+--------+---------------------+---------+
|  1 | first  | 2018-07-03 15:29:37 | hdfs    |
|  2 | second | 2018-07-03 15:30:57 | mr      |
|  3 | third  | 2018-07-03 15:31:07 | yarn    |
+----+--------+---------------------+---------+
3 rows in set (0.00 sec)

Mysql> exit;

[hadoop@172 sqoop]$ bin/sqoop-import --connect jdbc:mysql://$mysqlIP/test --username root 
-P --table sqoop_test --target-dir /sqoop

[hadoop@172 sqoop]$ hadoop fs -cat /sqoop/*
1, first, 2018-07-03 15:29:37.0,hdfs
2, second, 2018-07-03 15:30:57.0,mr
3, third, 2018-07-03 15:31:07.0,yarn

[hadoop@172 sqoop]$ mysql -h $mysqlIP –p
Enter password:
mysql> use test;
Database changed

mysql> create table sqoop_test_back(id int not null primary key auto_increment, title varchar(64), time timestamp, content varchar(255));
Query ok , 0 rows affected(0.00 sec)

mysql> show tables;                                                                     
+-----------------+
| Tables_in_test  |
+-----------------+
| sqoop_test      |
| sqoop_test_back |
+-----------------+
2 rows in set (0.00 sec)

mysql> exit;

[hadoop@172 sqoop]$ bin/sqoop-export --connect jdbc:mysql://$mysqlIP/test --username 
root -P --table sqoop_test_back --export-dir /sqoop

[hadoop@172 sqoop]$ mysql -h $mysqlIP –p
Enter password:
mysql> use test;
Database changed

mysql> select * from sqoop_test_back;
+----+---------+---------------------+---------+
| id | title   | time                | content |
+----+---------+---------------------+---------+
|  1 | first   | 2018-07-03 15:29:37 | hdfs   |
|  2 | second  | 2018-07-03 15:30:57 | mr      |
|  3 | third   | 2018-07-03 15:31:07 | yarn    |
+----+---------+---------------------+---------+
3 rows in set (0.00 sec)