Question

我正在尝试对以下类执行联接查询：

public class EquipmentCharacteristic {
    @DatabaseField(canBeNull = false, foreign = true, uniqueCombo = true)
    private Equipment equipment;

    @DatabaseField(canBeNull = false, foreign = true, uniqueCombo = true)
    private Characteristic characteristic;

    ...
}

public class Characteristic {
    ...
}

public class Equipment {
    ...
}

QueryBuilder的：

QueryBuilder<EquipmentCharacteristic, ?> daoEC = entityDAO.getDAO(
            EquipmentCharacteristic.class).queryBuilder();
daoEC.where().eq(EquipmentCharacteristic.EQUIPMENT + "_id", equipment.getId());

QueryBuilder<Characteristic, ?> daoCharacteristic = entityDAO.getDAO(
    Characteristic.class).queryBuilder();

return daoEC.join(daoCharacteristic)
    .selectRaw(
            "EquipmentCharacteristic." + EquipmentCharacteristic.ID, 
            "EquipmentCharacteristic." + EquipmentCharacteristic.EQUIPMENT + "_" + Equipment.ID, 
            "EquipmentCharacteristic." + EquipmentCharacteristic.POSSIBLE_VALUES, 
            "EquipmentCharacteristic." + EquipmentCharacteristic.CHARACTERISTIC + "_" + Characteristic.ID, 
            "EquipmentCharacteristic." + EquipmentCharacteristic.VALUE, 
            "Characteristic." + Characteristic.FIXED_VALUE, 
            "Characteristic." + Characteristic.UNIT, 
            "Characteristic." + Characteristic.CHARACTERISTIC)
    .queryRaw().closeableIterator();

问题是创建的查询与设备连接而不是特征：

SELECT 
    EquipmentCharacteristic.id, 
    EquipmentCharacteristic.equipment_id, 
    EquipmentCharacteristic.possibleValues, 
    EquipmentCharacteristic.characteristic_id, 
    EquipmentCharacteristic.value, 
    Characteristic.fixedValue, 
    Characteristic.unit, 
    Characteristic.characteristic 
FROM `EquipmentCharacteristic` INNER JOIN `Characteristic` ON `EquipmentCharacteristic`.`equipment_id` = `Characteristic`.`id`

如果我在设备之前将特性参考放在EquipmentCharacteristic中，则问题不会发生。

public class EquipmentCharacteristic {
    @DatabaseField(canBeNull = false, foreign = true, uniqueCombo = true)
    private Characteristic characteristic;

    @DatabaseField(canBeNull = false, foreign = true, uniqueCombo = true)
    private Equipment equipment;

    ...
}

有没有办法告知QueryBuilder应该用于连接的哪个表（类）？

感谢。

Answer 1

问题是创建的查询与设备连接而不是特征：

我很抱歉，但我无法重现这一点。我已经将以下测试添加到trunk。如果你能弄清楚为什么我的测试工作但代码失败，那将非常有帮助。

https://github.com/j256/ormlite-core/commit/78223c682aa0d7063c095afc0e26b466aeb618af

不幸的是，答案并不多。

ORMLite：有没有办法告知QueryBuilder应该用于连接的引用？

1 个答案: