The meaning of the SQL statement. how can this problem be solved?

SQL statement meaning DB: query (& quot; SELECTCOUNT (*) FROM & quot ;. DB: table ('vgallerys '). & quot; whereuidIN (meaning of SELECT & nbsp; pre_home_fri SQL statement
DB: query ("select count (*) FROM". DB: table ('vgallerys '). "where uid IN (SELECT

Pre_home_friend.fuid FROM pre_home_friend WHERE uid = '$ discuz_uid') and album = 0 ");
The meaning of this sentence cannot be understood ....... Hope you can help

------ Solution --------------------
Returns the number of records that meet the conditions.
After outputting SQL statements, you will know what the complete content is.

Echo "select count (*) FROM". DB: table ('vgallerys '). "where uid IN (SELECT

Pre_home_friend.fuid FROM pre_home_friend WHERE uid = '$ discuz_uid') and album = 0 ";
------ Solution --------------------
Find the total number of records in the vgallerys table that meet the uid in the range of "pre_home_friend this table uid is equal to $ discuz_uid" and album = 0