任何人都可以解决那个sql问题吗?

can any one solve that sql problem please? ex: i have library system project

table 1 for all items

id  title  item_tybe  volume_id
1   php    book       null
2   asp    magazine   1
2   perl   magazine   2

table 2 for volume which have related with table 1 but with magazine only

id  volume  approved
1   vol1    yes
1   vol2    no

i want get all items (book - magazine ) but i want get magazine which her volume approved = yes

should i should if condition ?? i dont know how please help

Assuming you meant you ONLY want to get magazines that are approved, whilst getting all books:

SELECT title, item_type
FROM table1
LEFT JOIN table2 ON table1.volume_id = table2.id AND table2.approved = 'yes'

Let me know if I misunderstood.

SELECT title, item_type FROM table1
LEFT JOIN table2 ON volume_id = table2.id
WHERE approved IS NULL or approved = 'yes'

try:

select * 
from table_1 t1
left join table_2 t2 on t1.volume_id=t2.id and t2.approved='yes'