Android OrmLite执行sql语句

我在OrmLite中有一个数据库。 此处是其中一个表-字段：

我想从表中删除一些值，如下所示：

List<Field> fields = fieldDao.queryForAll();
for (Field field : fields) {
    if (field.getType().equals("list") && field.getListValue().size() == 0) {
        fieldDao.delete(field);
    }
}

但是如何使用DeleteBuilder执行此查询

这段代码的问题是…选择COUNTlistValue FROM Field=0

您可以这样做

//get instance of DeleteBuilder
DeleteBuilder<Field, Integer> deleteBuilder = fieldDao.deleteBuilder();
//construct yours WHERE
//in this exampe we select fields with "id"=0
deleteBuilder.where().eq("id", 0);
//call delete
deleteBuilder.delete();

如果要删除行，在代码条件之后，可以形成要删除的对象的ArrayList，然后将其ID传递给deleteBuilder where语句，如下所示

List<Integer> ids= new ArrayList<Integer>();
List<Field> fields = fieldDao.queryForAll();
List<Field> fieldsToDelete = new ArrayList<Field>();
for (Field field : fields) 
{
    if (field.getType().equals("list") && field.getListValue().size() == 0)
    {
        ids.add(field.getId);
        fieldsToDelete.add(field);
    }
}
fieldDao.delete(ids);
//or
fieldDao.delete(fieldsToDelete);
//or
//get instance of DeleteBuilder
DeleteBuilder<Field, Integer> deleteBuilder = fieldDao.deleteBuilder();
//construct yours WHERE
//in this exampe we select fields with "id"=0
deleteBuilder.where().in("id", ids);
//call delete
deleteBuilder.delete();

但是如何使用DeleteBuilder执行此查询

没有一种直接的方法可以使用DeleteBuilder来实现这一点，因为外来对象实际上在Field类中没有任何信息

但是，这里有一种方法可以使用原始查询然后使用DeleteBuilder来实现这一点

近似代码：

qb = fieldListValueDao.queryBuilder();
// raw query for the field_ids in the fieldListValue table
rawResults = qb.queryRaw("SELECT field_id FROM fieldListValue GROUP BY field_id",
    new RawRowMapper<Integer>() {
        // each result row is a single integer in the 0th column
        public Integer mapRow(String[] columnNames, String[] resultColumns) {
            return Integer.parseInt(resultColumns[0]);
        }
    });

您还可以使用notInid、queryBuilder方法完成此操作：

我需要检查一下，以确保

---

希望这有帮助。

看起来不太简洁。请查看更新的答案。无论如何，您应该形成一个要删除的对象或其ID的集合。

qb = fieldListValueDao.queryBuilder();
// raw query for the field_ids in the fieldListValue table
rawResults = qb.queryRaw("SELECT field_id FROM fieldListValue GROUP BY field_id",
    new RawRowMapper<Integer>() {
        // each result row is a single integer in the 0th column
        public Integer mapRow(String[] columnNames, String[] resultColumns) {
            return Integer.parseInt(resultColumns[0]);
        }
    });

deleteBuilder = fieldDao.deleteBuilder();
// delete any rows that are not in the raw-results -- who have no fieldListValue entries
deleteBuilder.where().notIn("id", rawResults);
deleteBuilder.delete();

qb = fieldListValueDao.queryBuilder();
qb.selectColumns("field_id");
qb.groupBy("field_id");
...
deleteBuilder = fieldDao.deleteBuilder();
deleteBuilder.where().notIn("id", qb);
deleteBuilder.delete();