mysql's method of getting data by time period

The time format is 2013-03-12
Query the data of the day:

SELECT * FROM `table` WHERE date( The time field ) = curdate(); 

Query out the current month field:

SELECT * 
FROM `table` 
WHERE month(  The time field ) = month( now( ) ) ; 

The time format is 1219876... UNIX time, simply apply the "FROM_UNIXTIME()" function
For example, query month:

SELECT * 
FROM `table` 
WHERE month( from_unixtime( reg_time ) ) = month( now( ) ) ; 

What about the last month? Change 1!

SELECT * 
FROM `table` 
WHERE month( from_unixtime( reg_time ) ) = month( now( ) ) -1;