mysql 什么是最好的查询?

sczxawaw  于 2022-10-31  发布在  Mysql
关注(0)|答案(2)|浏览(99)

我有公交车、街道、去程、回程的表
在餐桌街我有
示例:

id | name
1  | street1 
2  | street2
3  | street4
...
n  | streetn

表route_going,我有示例:

id_bus | id_street | order
101    | 1         | 1
101    | 2         | 2
101    | 5         | 3

...

表route_return,我有例子:

id_bus | id_street | order
101    | 3         | 1
101    | 2         | 2
101    | 1         | 3

...

好的,在这个例子中,公交车101从街道1,2和5按这个顺序行驶,公交车从街道3,2和1按这个顺序返回。
我想知道哪些公交车经过街道“x”和街道“y”(先经过x,后经过y)
例如:

x = 1, y = 5 -> the bus 101 pass
x = 1, y = 3 -> the bus 101 pass
x = 3, y = 1 -> the bus 101 pass
x = 3, y = 5 -> the bus 101 don't pass

因此,我用于发现公交车的sql是...(例如,1号和5号街道的过路情况)

select * from bus as b where 
-- The bus passes between the 2 streets at the going route??
exists (select * from route_going as rg1, route_going as rg2,street as r1,street as r2 where rg1.id_bus = rg2.id_bus and rg1.id_street = r1.id and rg2.id_street = r2.id and r1.id = 1 and r2.id = 5 and b.bus_id = rg1.id_bus and rg1.order <= rg2.order)
-- The bus passes between the 2 streets at the return route??
or exists (select * from route_return as rg1, route_return as rg2,street as r1,street as r2 where rg1.id_bus = rg2.id_bus and rg1.id_street = r1.id and rg2.id_street = r2.id and r1.id = 1 and r2.id = 5 and b.bus_id = rg1.id_bus and rg1.order <= rg2.order)
-- The bus passes between the 2 streets at the going route first and return route later??
or exists (select * from route_going as rg1, route_return as rg2,street as r1,street as r2 where rg1.id_bus = rg2.id_bus and rg1.id_street = r1.id and rg2.id_street = r2.id and r1.id = 1 and r2.id = 5 and b.bus_id = rg1.id_bus)

所以,我认为这个查询不好。谁能帮我说一下这个搜索的“最好”查询是什么?

z9ju0rcb

z9ju0rcb1#

SET @x = 1;
SET @y = 5;

SELECT x.id_bus
  FROM   
     ( SELECT *,0 returning FROM route_going UNION SELECT *, 1 FROM route_return ) x
  JOIN
     ( SELECT *,0 returning FROM route_going UNION SELECT *, 1 FROM route_return ) y
    ON y.id_bus = x.id_bus
   AND (y.returning > x.returning OR (y.returning = x.returning AND y.porder > x.porder))
 WHERE x.id_street = @x
   AND y.id_street = @y;
t9aqgxwy

t9aqgxwy2#

select 
street.name,
route_going.id_bus,route_going.id_street
route_return.id_bus,route_return.id_street
on street.id=route_going.id_street and 
route_return.id_street=route_going.id_street;

试试这个.谢谢

相关问题