184 个回答
如何更新license文件
查看物理文件的license信息，执行： license() 注意，上述函数查到的不是内存里面的license信息，而是物理文件dolphindb.lic里面的信息。 用于查看当前节点的license过期时间。可用于更新license之后，验证新的license是否生效。函数为： getLicenseExpiration() 1 在线更新license step1：用新的dolphindb.lic文件替...
回答于 2022-03-17 18:24
ReactiveStateEngine error " Can't find the corresponding rea...
If you want to de duplicate in streaming calculation, you can select the keyedStreamTable. reference resources: keyedStreamTable
回答于 2022-01-17 10:16
How to calculate the following in real time with every tick
time = (0..9)*1000*60*5 + now() symbol = take("00001", 10) open = take(1..11, 10) t = table(time, symbol, open) result = table(1:0, `symbol`time`mavgOpen, [SYMBOL, TIMESTAMP, DOUBLE]) createReactiveStateEngine(name="reactiveDemo", metrics =[<time>, <mavg(open, 3)>], dummyTable=t, outpu...
回答于 2022-01-17 10:06
createDailyTimeSeriesEngine doesnot align time according to...
Time series engine includes createDailyTimeSeriesEngine and createTimeSeriesEngine, Their rounding rules are different from the dailyAlignedBar. In order to observe and compare the calculation results, the system will adjust the start time of the first data window, and determine the integer type adj...
回答于 2022-01-10 09:25
SQL查询时如何将同一个分组的值存在一个列中？
提供一种解决方法： select concat(string(value), ",") from table1 group by id
回答于 2022-01-07 16:20
如何查询出一个表中所有含NULL值的记录
可以尝试一下下面的查询语句： x1 = 1 NULL 2 NULL NULL x2 = 1 NULL NULL 3 4 x3 = 3 NULL 3 4 5 t = table(x1 ,x2 ,x3) t[each(isNull, t.values()).rowOr()] 结果：
回答于 2021-12-17 10:23
如何复用已创建的schema的信息
以 csv 文本文件为例，示例代码如下 def getFileSchemaName(filePath){ schema = extractTextSchema(filePath) name = string(NULL) for (i in schema.name){ name = name + "`" + i } return name } def getFileSchemaType(filePath){ schema = extractTextSchema(filePath) type = string(NULL) for (i in sch...
回答于 2021-11-25 09:56
请教 实时从接收 tick 数据到生成 1分钟K线的流程
参考如下代码： //////// ticks 表 /////// 表的 各 列 和 数据类型, 并建一张空表 tbColNames= `TradingDay`InstrumentID`ExchangeID`ExchangeInstID`LastPrice`Volume`Amount`OpenPosition`PreSettlementPrice`PreClosePrice`PreOpenInterest`OpenPrice`HighestPrice`LowestPrice`TotalVolume`TotalTurnover`OpenIntere...
回答于 2021-09-28 09:20
想订阅并合成K线，请帮我看看错在哪里
参考如下代码： //////// ticks 表 /////// 表的 各 列 和 数据类型, 并建一张空表 tbColNames= `TradingDay`InstrumentID`ExchangeID`ExchangeInstID`LastPrice`Volume`Amount`OpenPosition`PreSettlementPrice`PreClosePrice`PreOpenInterest`OpenPrice`HighestPrice`LowestPrice`TotalVolume`TotalTurnover`OpenIntere...
回答于 2021-09-28 09:19