Importing into MySQL from a file:
C :\mysql\bin> mysqlimport [options] dbname filename.txt       [See in MySQL Manual 4.8.7]
or
mysql> use dbname;
mysql> LOAD DATA INFILE 'filename.txt'        [See in MySQL Manual 6.4.9]
        -> [REPLACE | INGNORE]
        -> INTO TABLE table_name
        -> [FIELDS
        ->   [TERMINATED BY '\t']
        ->   [[OPTONALLY] ENCLOSED BY ' " ']
        ->   [ESCAPED BY '\n']]
        -> [INGORDE num LINES];

Exporting from MySQL to a file:
C :\mysql\bin> mysqldump [options] dbname [tables] > filename.txt        [See in MySQL Manual 4.8.5]
or
mysql> use dbname;
mysql> SELECT *                             [See in MySQL Manual 6.4.1]
        -> INTO OUTFILE 'filename.txt'
        -> [FIELDS
        ->   [TERMINATED BY '\t']
        ->   [[OPTONALLY] ENCLOSED BY ' " ']
        ->   [ESCAPED BY '\n']]
        -> FROM table_name

Example:
Creating a backup of a database and importing a backup file.
Making a backup:
C :\mysql\bin> mysqldump --opt visualtech_db > visualtech_backup.sql  
Inserting a backup
C :\mysql\bin> mysql -u root -p visualtech_cb < visualtech_backup.sql