SELECT
*
FROM
COURSE
WHERE
Course_number IN ( SELECT Pererquisite_number FROM PREREQUISITE WHERE Course_number = 'CS3308' )
查询以检索“CS3308”课程的先决条件的课程名称。
课程表是主表
PREREQUISITE表是课程先决表。请问这个用MangoDB aggregate 的$lookup怎么查询?
db.orders.aggregate([
{
$lookup:
{
from: "inventory",
localField: "item",
foreignField: "sku",
as: "inventory_docs"
}
}
])
SELECT *, inventory_docs
FROM orders
WHERE inventory_docs IN (SELECT *
FROM inventory
WHERE sku= orders.item);
我看过这个结构,orders.item 我怎么修改为固定的值CS3308?