Android-kotlin中MySql查询到SQL房间查询的转换

我刚从后端得到下面的mysql查询。 我必须使用Android中的Room数据库在本地管理这些东西

因此，后端查询如下：

Select DATE_FORMAT(timeStamp ,'%d-%b') AS date, DATE_FORMAT(timeStamp ,'%d') AS dateNumber, 
ROUND(AVG(IF(stateOfCharge IS NULL, 0, stateOfCharge)), 2) AS chargeOverTime, 
ROUND(AVG(IF(temperature IS NULL, 0, temperature)), 2) AS temperature, 
ROUND(AVG(IF(current IS NULL, 0, current)), 2) AS averageChargeDischarge 
from batteryDetails 
where name="VERNE000003"
and timeStamp between "2021-03-11 11:40:29" AND "2021-03-12 23:40:29"
Group by DATE_FORMAT(timeStamp ,"%Y-%m-%d") ORDER BY timeStamp;

@Query("SELECT datetime(timeStamp ,'%d-%b') AS date, " +
        "datetime(timeStamp ,'%d') AS dateNumber, " +
        "ROUND(AVG(if(stateOfCharge IS NULL, 0, stateOfCharge)), 2) AS chargeOverTime, " +
        "ROUND(AVG(if(temperature IS NULL, 0, temperature)), 2) AS temperature, " +
        "ROUND(AVG(if(current IS NULL, 0, current)), 2) AS averageChargeDischarge " +
        "FROM " + DatabaseConstant.mUserBatteryDetailsTable +
        " WHERE name= :batteryId and timeStamp between :startDate AND :endDate " +
        "GROUP BY datetime(timeStamp ,'%Y-%m-%d') ORDER BY timeStamp")
suspend fun getHistoryData(batteryId: String, startDate: String, endDate: String): List<BatteryDetails>?

 @Query("Select strftime('%d %m',datetime(timeStamp, 'unixepoch')) as dates, " +
        "strftime('%d', datetime(timeStamp, 'unixepoch')) as dateNumber, " +
        "round(avg(coalesce( stateOfCharge,0))) as chargeOverTime, " +
        "ROUND(AVG(coalesce( avgTemperature,0))) as avgTemperature, " +
        "ROUND(AVG(coalesce(current,0))) as averageChargeDischarge " +
        "FROM " + DatabaseConstant.mUserBatteryDetailsTable +
        " WHERE name= :batteryId and timeStamp between :startDate AND :endDate " +
        "Group by datetime(timeStamp ,'%Y-%m-%d') ORDER BY timeStamp")

我已尝试按以下方式购买：

Select DATE_FORMAT(timeStamp ,'%d-%b') AS date, DATE_FORMAT(timeStamp ,'%d') AS dateNumber, 
ROUND(AVG(IF(stateOfCharge IS NULL, 0, stateOfCharge)), 2) AS chargeOverTime, 
ROUND(AVG(IF(temperature IS NULL, 0, temperature)), 2) AS temperature, 
ROUND(AVG(IF(current IS NULL, 0, current)), 2) AS averageChargeDischarge 
from batteryDetails 
where name="VERNE000003"
and timeStamp between "2021-03-11 11:40:29" AND "2021-03-12 23:40:29"
Group by DATE_FORMAT(timeStamp ,"%Y-%m-%d") ORDER BY timeStamp;

@Query("SELECT datetime(timeStamp ,'%d-%b') AS date, " +
        "datetime(timeStamp ,'%d') AS dateNumber, " +
        "ROUND(AVG(if(stateOfCharge IS NULL, 0, stateOfCharge)), 2) AS chargeOverTime, " +
        "ROUND(AVG(if(temperature IS NULL, 0, temperature)), 2) AS temperature, " +
        "ROUND(AVG(if(current IS NULL, 0, current)), 2) AS averageChargeDischarge " +
        "FROM " + DatabaseConstant.mUserBatteryDetailsTable +
        " WHERE name= :batteryId and timeStamp between :startDate AND :endDate " +
        "GROUP BY datetime(timeStamp ,'%Y-%m-%d') ORDER BY timeStamp")
suspend fun getHistoryData(batteryId: String, startDate: String, endDate: String): List<BatteryDetails>?

 @Query("Select strftime('%d %m',datetime(timeStamp, 'unixepoch')) as dates, " +
        "strftime('%d', datetime(timeStamp, 'unixepoch')) as dateNumber, " +
        "round(avg(coalesce( stateOfCharge,0))) as chargeOverTime, " +
        "ROUND(AVG(coalesce( avgTemperature,0))) as avgTemperature, " +
        "ROUND(AVG(coalesce(current,0))) as averageChargeDischarge " +
        "FROM " + DatabaseConstant.mUserBatteryDetailsTable +
        " WHERE name= :batteryId and timeStamp between :startDate AND :endDate " +
        "Group by datetime(timeStamp ,'%Y-%m-%d') ORDER BY timeStamp")

@Query（“选择日期时间（时间戳，%d-%b”）作为日期，”+
datetime（时间戳“%d”）作为日期编号+
四舍五入（平均值（如果（充电状态为空，0，充电状态）），2）作为充电超时+
四舍五入（平均值（如果（温度为零，0，温度）），2）作为温度+
“四舍五入（平均值（如果（电流为零，0，电流）），2）作为平均电荷放电”+
“FROM”+DatabaseConstant.muserbatterydailstable+
“其中name=：batteryId和时间戳介于：startDate和：endDate之间”+
“按日期时间分组（时间戳，%Y-%m-%d'）按时间戳排序”）
suspend fun getHistoryData（batteryId:String，startDate:String，endDate:String）：列表？

但下面是一个错误：

错误：查询有问题：[SQLITE_error]SQL错误或 缺少数据库（没有这样的函数：if） 公共抽象java.lang.Object getHistoryData（@org.jetbrains.annotations.NotNull（）

---

查询结果如下：

Select DATE_FORMAT(timeStamp ,'%d-%b') AS date, DATE_FORMAT(timeStamp ,'%d') AS dateNumber, 
ROUND(AVG(IF(stateOfCharge IS NULL, 0, stateOfCharge)), 2) AS chargeOverTime, 
ROUND(AVG(IF(temperature IS NULL, 0, temperature)), 2) AS temperature, 
ROUND(AVG(IF(current IS NULL, 0, current)), 2) AS averageChargeDischarge 
from batteryDetails 
where name="VERNE000003"
and timeStamp between "2021-03-11 11:40:29" AND "2021-03-12 23:40:29"
Group by DATE_FORMAT(timeStamp ,"%Y-%m-%d") ORDER BY timeStamp;

@Query("SELECT datetime(timeStamp ,'%d-%b') AS date, " +
        "datetime(timeStamp ,'%d') AS dateNumber, " +
        "ROUND(AVG(if(stateOfCharge IS NULL, 0, stateOfCharge)), 2) AS chargeOverTime, " +
        "ROUND(AVG(if(temperature IS NULL, 0, temperature)), 2) AS temperature, " +
        "ROUND(AVG(if(current IS NULL, 0, current)), 2) AS averageChargeDischarge " +
        "FROM " + DatabaseConstant.mUserBatteryDetailsTable +
        " WHERE name= :batteryId and timeStamp between :startDate AND :endDate " +
        "GROUP BY datetime(timeStamp ,'%Y-%m-%d') ORDER BY timeStamp")
suspend fun getHistoryData(batteryId: String, startDate: String, endDate: String): List<BatteryDetails>?

 @Query("Select strftime('%d %m',datetime(timeStamp, 'unixepoch')) as dates, " +
        "strftime('%d', datetime(timeStamp, 'unixepoch')) as dateNumber, " +
        "round(avg(coalesce( stateOfCharge,0))) as chargeOverTime, " +
        "ROUND(AVG(coalesce( avgTemperature,0))) as avgTemperature, " +
        "ROUND(AVG(coalesce(current,0))) as averageChargeDischarge " +
        "FROM " + DatabaseConstant.mUserBatteryDetailsTable +
        " WHERE name= :batteryId and timeStamp between :startDate AND :endDate " +
        "Group by datetime(timeStamp ,'%Y-%m-%d') ORDER BY timeStamp")

---

用大小写替换IF（）。@Akina谢谢mam，现在得到：“SQL错误或缺少数据库（近”）”：语法错误）“请。指南。

如果（A，B，C）

=>

当A然后B其他C结束时的情况

。但是在您的情况下，

IF（column为NULL，0，column）

可以替换为

COALESCE（column，0）

。在任何数据库（Access除外）中，

IF（stateOfCharge为NULL，0，stateOfCharge）

的等价物是

COALESCE（stateOfCharge，0）