postgresql - Sub Query in select clause with Squeryl

Question

I'm trying to replicate the following query usine Squeryl.

SELECT c.order_number,p.customer,p.base,( 
  SELECT sum(quantity) FROM "Stock" s where s.base = p.base  
) as stock 
FROM "Card" c, "Part" p WHERE c."partId" = p."idField";

I have the following code for selecting the Cards and Parts but I cannot see a way to add a sumation into the select clause.

from(cards, parts)((c,p) => 
where(c.partId === p.id)    
select(c,p)

Any help is much appreciated!

Answer 1

在 Squeryl 中，您可以Queryable在查询的 from 子句中使用任何对象。因此，要创建子查询，类似以下内容应该适合您：

def subQuery = from(stock)(s => groupBy(s.base) compute(sum(s.quantity)))

from(cards, parts, subquery)((c, p, sq) =>
  where(c.partId === p.idField and sq.key === p.base)
  select(c.orderNumber, p.customer, sq.measures))

当然，字段名称可能略有不同，只是猜测类定义。如果您想要整个对象cards而parts不是原始查询中的单个字段 - 只需将 select 子句更改为：select(c, p, sq.measures)