Database Files-Related Issue
Answer to your first question: Each file contains info for the table


cars.frm has the table structure
cars.MYD has the table data
cars.MYI has the table indexes


Given this layout, the cars table uses the storage engine MyISAM.

Answer to your second question: Yes, provided the following circumstances


every table uses the storage engine MyISAM
no INSERTs, UPDATEs, or DELETEs are running
DB Connections using TCP/IP are disabled


To check to see if all the tables are MyISAM, run this query:

SELECT COUNT(1) TableCount,engine
FROM information_schema.tables
WHERE table_schema='db_test_1'
GROUP BY engine;


You should only see just MyISAM. If you see other storage engines, you cannot just copy.

If your root@localhost password is mypass, here is all you need to to safely move all the tables regardless of storage engine:

# USERPASS="-uroot -pmypass"
# service mysql restart --skip-networking
# mysql ${USERPASS} -A -e"CREATE DATABASE db_test_2"
# mysqldump ${USERPASS} --routines --triggers db_test_1 | mysql ${USERPASS} -A -Ddb_test_2
# service mysql restart


If the data is huge, do this instead:

# USERPASS="-uroot -pmypass"
# service mysql restart --skip-networking
# mysql ${USERPASS} -A -e"CREATE DATABASE db_test_2"
# mysqldump ${USERPASS} --routines --triggers db_test_1 &gt; /root/MyData.sql
# mysql ${USERPASS} -A -Ddb_test_2 &lt; /root/MyData.sql
# service mysql restart


Give it a Try !!!