使用 Android 版 ORMLite,我需要构建一个按订单 ID 或客户名称返回订单的查询。请考虑以下类声明:
@DatabaseTable(tableName = "order")
public class Order {
@DatabaseField(generatedId = true)
private Long id;
@DatabaseField(foreign = true, canBeNull = false, foreignAutoRefresh = true, columnName = "customer_id")
private Customer customer;
// default constructor, getters and setters...
}
@DatabaseTable(tableName = "customer")
public class Customer {
@DatabaseField(generatedId = true)
private Long id;
@DatabaseField
private String name;
// default constructor, getters and setters...
}
我正在寻找的原始 SQL 是这样的:
SELECT
o.*
FROM
order o
JOIN customer c on
o.customer_id = c.id
WHERE
(o.id = ?) OR (c.name = ?)
使用 ORMLite 执行此操作的最佳方法是什么?
ORMLite http://ormlite.com/现在支持简单的连接查询 http://ormlite.com/docs/join-queries.
所以你的查询看起来像这样:
QueryBuilder<Customer, Integer> customerQb = customerDao.queryBuilder();
SelectArg nameSelectArg = new SelectArg();
// this gives the c.name = ?
customerQb.where().eq("name", nameSelectArg);
QueryBuilder<Account, Integer> orderQb = orderDao.queryBuilder();
SelectArg idSelectArg = new SelectArg();
// this gives the o.id = ?
orderQb.where().eq("id", idSelectArg);
orderQb.join(customerQb);
// then you set the args and run the query
nameSelectArg.setValue("jim");
idSelectArg.setValue(1);
List<Order> results = orderQb.join(customerQb).query();
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