使用Linq对数据库进行多GroupBy查询
现状：
Oracle数据库，某表中的数据3000万行
目标：
先按照年进行分组，然后按照月分组，再按照日分组，再按照小时分组，最后统计。
问题：
通过年进行分组，统计，很简单。一句group by就行。
但是如果先按照年进行分组，然后以年进行了分组的组里，再按照月分组，尝试了多次使用group by，结果EF不支持。
解决
只需要写一个group by，但以一个自己组合的object进行分组即可。
示例
请注意看
group x by new
{
x.处理时间!.Value.Year,
x.处理时间!.Value.Month,
x.处理时间!.Value.Day
} into g
这一句。
private object GetBookBRCountByDay(DateTime startDateTime, DateTime endDateTime)
{
var data = from x in oracleDbContext.流通日志
where x.处理时间.HasValue
&& x.处理时间.Value >= startDateTime
&& x.处理时间.Value <= endDateTime
group x by new { x.处理时间!.Value.Year, x.处理时间!.Value.Month, x.处理时间!.Value.Day } into g
select new
{
yearMonthDay = g.Key,
JCounts = g.Where(x => x.操作类型 == "J").Count(),
HCounts = g.Where(x => x.操作类型 == "H").Count(),
XCounts = g.Where(x => x.操作类型 == "X").Count(),
};
//从数据库返回数据
var dataList = data.ToList();
//遍历每一年
List<object> yearCounts = new();
foreach (var year in Enumerable.Range(startDateTime.Year, endDateTime.Year - startDateTime.Year + 1))
{
//遍历每一月
List<object> monthCounts = new();
foreach (var month in Enumerable.Range(1, 12))
{
//遍历每一天
List<object> dayCounts = new();
foreach (var day in Enumerable.Range(1, 31))
{
var jCounts = dataList
.Where(x => x.yearMonthDay.Year == year
&& x.yearMonthDay.Month == month
&& x.yearMonthDay.Day == day)
.Select(x => x.JCounts)
.Sum();
var hCounts = dataList
.Where(x => x.yearMonthDay.Year == year
&& x.yearMonthDay.Month == month
&& x.yearMonthDay.Day == day)
.Select(x => x.HCounts)
.Sum();
var xCounts = dataList
.Where(x => x.yearMonthDay.Year == year
&& x.yearMonthDay.Month == month
&& x.yearMonthDay.Day == day)
.Select(x => x.XCounts)
.Sum();
if ((xCounts | hCounts | xCounts) > 0)
{
dayCounts.Add(new
{
day = day,
counts = new BookBRCount
{
borrowCount = jCounts,
returnCount = hCounts,
renewCount = xCounts,
}
});
}
}
if (dayCounts.Count() > 0)
{
monthCounts.Add(new
{
month = year,
months = dayCounts
});
}
}
if (monthCounts.Count() > 0)
{
yearCounts.Add(new
{
year = year,
years = monthCounts
});
}
}
return yearCounts;
}
EF生成的SQL语句
Executed DbCommand (112ms)
[Parameters=[:startDateTime_0='?' (DbType = Date), :endDateTime_1='?' (DbType = Date)],
CommandType='Text',
CommandTimeout='0']
SELECT "t"."Year", "t"."Month", "t"."Day", "t"."Hour", COUNT(CASE
WHEN "t"."操作类型" = 'J' THEN 1
END) "JCounts", COUNT(CASE
WHEN "t"."操作类型" = 'H' THEN 1
END) "HCounts", COUNT(CASE
WHEN "t"."操作类型" = 'X' THEN 1
END) "XCounts"
FROM (
SELECT "流"."操作类型",
EXTRACT(YEAR FROM "流"."处理时间") "Year",
EXTRACT(MONTH FROM "流"."处理时间") "Month",
EXTRACT(DAY FROM "流"."处理时间") "Day",
TO_NUMBER(TO_CHAR("流"."处理时间", 'HH24')) "Hour"
FROM "GDLISNET"."流通日志" "流"
WHERE (((("流"."处理时间" IS NOT NULL)
AND ("流"."处理时间" >= :startDateTime_0)))
AND ("流"."处理时间" <= :endDateTime_1))
) "t"
GROUP BY "t"."Year", "t"."Month", "t"."Day", "t"."Hour"
执行结果
{
"level": "hour",
"startDateTime": "2023-03-22T00:00:00",
"endDateTime": "2023-03-22T19:00:00",
"data": [
{
"year": 2023,
"years": [
{
"month": 3,
"months": [
{
"day": 22,
"days": [
{
"hour": 8,
"counts": {
"borrowCount": 0,
"returnCount": 9,
"renewCount": 0
}
},
{
"hour": 9,
"counts": {
"borrowCount": 28,
"returnCount": 36,
"renewCount": 0
}
},
{
"hour": 10,
"counts": {
"borrowCount": 4,
"returnCount": 3,
"renewCount": 0
}
},
{
"hour": 11,
"counts": {
"borrowCount": 14,
"returnCount": 6,
"renewCount": 0
}
},
{
"hour": 12,
"counts": {
"borrowCount": 14,
"returnCount": 10,
"renewCount": 1
}
},
{
"hour": 13,
"counts": {
"borrowCount": 8,
"returnCount": 8,
"renewCount": 0
}
},
{
"hour": 14,
"counts": {
"borrowCount": 19,
"returnCount": 20,
"renewCount": 1
}
},
{
"hour": 15,
"counts": {
"borrowCount": 22,
"returnCount": 22,
"renewCount": 0
}
},
{
"hour": 16,
"counts": {
"borrowCount": 34,
"returnCount": 21,
"renewCount": 19
}
},
{
"hour": 17,
"counts": {
"borrowCount": 23,
"returnCount": 22,
"renewCount": 0
}
},
{
"hour": 18,
"counts": {
"borrowCount": 3,
"returnCount": 0,
"renewCount": 3
}
}
]
}
]
}
]
}
]
}