user
+ userid : int+ username : char+ usersex : char+ userage : char+ userpwd : char
+ add() : char+ delete() : char+ alter() : char+ query() : char
book
+ bookid : int+ bookname : char+ writerid : int+ writername : char+ category : char+ description : char+ photo : char+ text :char
manager
+ managerid : int+ managername : char+ managersex : char+ managerage : char+mnnagerpwd : char
writer
+ writerid : int+ writername : char+ writersex : char+ writerage : char+ writerpwd : char
collect
+ bookid : int+ bookname : char+ writerid : int+ writername : char+ indate : date+ outdate : date+ photo : char+ text :char+ description ： char
+ add() : char+ delete() : char + query() : char
advise
+ adviseid : int+ adcontent : char+ userid : int + advisedate : char+ result : char
