[英]Reading a value from Entity B when reading Entity A (left join on non PK column) - JPA 2.0
[英]Store non existence column in JPA entity when it is used as Alias in SQL
我已編寫查詢來計算指定企業下可用位置的數量。 SQL查詢是這樣的
SELECT
e.enterprise_id,
e.ent_name,
(
SELECT count(l.location_id)
FROM rfx_ent_locations l
WHERE l.loc_type_id <> 1001
AND e.enterprise_id = l.enterprise_id
) AS locCount
FROM rfx_enterprises e
WHERE e.partner_type = 102;
如果將其作為實體中的列進行介紹,則會收到一條錯誤消息,指出未找到任何列。 要檢索包含用作別名的locCount的實體,應使用JPA如何進行?
不要用那做計數查詢。像這樣單獨做
Query query = session.createQuery("SELECT count(l.location_id)
FROM rfx_ent_locations l
WHERE l.loc_type_id <> 1001
AND e.enterprise_id = l.enterprise_id");// do as you please with the query result
/**
* instead of doing a second query to get the count. Just do a quick count using Iterator
*/
for (Iterator iterator = query.iterate(); iterator.hasNext();) {
iterator.next();
count++;
}
Integer queryCount = count;
將此queryCount設置為類中的@transient變量setter方法,這樣您就可以進行計數了
要么
這樣嘗試
Integer count = (Integer) session.CreateQuery("SELECT count(l.location_id)
FROM rfx_ent_locations l
WHERE l.loc_type_id <> 1001
AND e.enterprise_id = l.enterprise_id").UniqueResult();
干杯!!!
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