按月分组的不那么笨拙的方式？
Less clumsy way of grouping by month?
我按月对数据进行分组，结果应该是 Date.
类型
我发布的示例目前有效，但我发现它太长太笨拙，因为我必须解析最终日期以用作分组。
无论如何，这是整个脚本：
declare @table table
(
ReportDate date,
Sales int
)
insert into @table
select '11/5/2018', 1 union
select '11/8/2018', 3 union
select '3/5/2019', 2 union
select '3/8/2019', 6 union
select '4/1/2019', 5
select
cast(CAST(MONTH(reportdate) AS VARCHAR(2)) + '/1/' + CAST(year(reportdate) AS VARCHAR(4)) as date) as 'MonthOfYear',
SUM(sales) as 'sales' FROM @table
group by
cast(CAST(MONTH(reportdate) AS VARCHAR(2)) + '/1/' + CAST(year(reportdate) AS VARCHAR(4)) as date)
order by cast(CAST(MONTH(reportdate) AS VARCHAR(2)) + '/1/' + CAST(year(reportdate) AS VARCHAR(4)) as date)
哪个returns:
MonthOfYear sales
2018-11-01 4
2019-03-01 8
2019-04-01 5
结果是正确的，但我觉得这很笨拙而且很长。是否有更紧凑的按月分组的方法，其中结果的类型为 Date?
我假设你在寻找格式：
DECLARE @d DATETIME = '10/01/2011';
SELECT FORMAT ( @d, 'd', 'en-US' ) AS 'US English Result'
,FORMAT ( @d, 'd', 'en-gb' ) AS 'Great Britain English Result'
,FORMAT ( @d, 'd', 'de-de' ) AS 'German Result'
,FORMAT ( @d, 'd', 'zh-cn' ) AS 'Simplified Chinese (PRC) Result';
SELECT FORMAT ( @d, 'D', 'en-US' ) AS 'US English Result'
,FORMAT ( @d, 'D', 'en-gb' ) AS 'Great Britain English Result'
,FORMAT ( @d, 'D', 'de-de' ) AS 'German Result'
,FORMAT ( @d, 'D', 'zh-cn' ) AS 'Chinese (Simplified PRC) Result';
更多详情：
https://docs.microsoft.com/en-us/sql/t-sql/functions/format-transact-sql?view=sql-server-ver15
结果：
将日期更改为 2008 年月初的常用方法是使用 DATEADD 和 DATEDIFF 来代替日期 0（又名 19000101）：
SELECT CONVERT(date,DATEADD(MONTH,DATEDIFF(MONTH,0,T.ReportDate),0)) AS MonthDate,
SUM(Sales) AS TotalSales
FROM @table T
GROUP BY DATEADD(MONTH,DATEDIFF(MONTH,0,T.ReportDate),0);
如果您使用的是 2012+（您确实应该使用 2008，现在 完全 不受支持），您可以使用 EOMONTH 和 DATEADD:
SELECT DATEADD(DAY, 1, EOMONTH(T.ReportDate,-1)) AS MonthDate,
SUM(Sales) AS TotalSales
FROM @table T
GROUP BY DATEADD(DAY, 1, EOMONTH(T.ReportDate,-1));
这样做的好处是不必将 CAST/CONVERT 表达式返回到 date（因为 0 或 '19000101' 会被解释为作为 datetime).
有用的提示。提供日期时，请避免使用模棱两可的格式。我得到的结果与您的预期结果 不 相同，因为像 '11/5/2018' 这样的日期意味着 2018 年 5 月 11 日。考虑到您的所有日期在 d/M/yyyy 和 M/d/yyyy 格式，这使得它更加混乱。当为 SQL 服务器问题提供日期时，yyyyMMdd 和 yyyy-MM-DDThh:mm:ss.nnnnnnn 是最好的格式，因为它们没有歧义。
+'-01'可选
Select MonthOfYear = convert(varchar(7),ReportDate,120)+'-01'
,Sales = sum(Sales)
From @table
Group BY convert(varchar(7),ReportDate,120)
Returns
MonthOfYear Sales
2018-11-01 4
2019-03-01 8
2019-04-01 5
EDIT
而不是 convert()，您可以使用隐式转换并使用
left(ReportDate,7)
如果您使用 Calendar table，基于日期的报告变得 很多 更容易和更快。日历 table 包含下一个（例如 50 年）所有日期的条目，具有年、季度、学期、月、月中日、年中日、星期几、周数等的明确列。Date 是主键，其余列根据报告需要编制索引。
假设您创建一个 table，每个日期的 StartOfMonth 都有一个额外的列，查询可以变得像这样简单：
SELECT StartOfMonth,sum(Sales)
FROM @table inner join Calendar on Calendar.Date=ReportDate
GROUP BY StartOfMonth
select cast(yyyymm + '01' as date) as MonthOfYear,
SUM(sales) as sales
from @table cross apply (select convert(char(6),ReportDate, 112) as yyyymm)a
group by yyyymm
order by MonthOfYear;
我会看看@Panagiotis Kanavos 的日历 Table 并给你一个 虚拟索引。使用 rangeAB（下面的 DDL），您可以 group/sort/Aggregate/order/de-duplicate/etc 而无需创建索引 .
-- Your data (no index)
declare @table table
(
ReportDate date,
Sales int
)
insert @table VALUES ('11/5/2018',1),('11/8/2018',3),('3/5/2019',2),('3/8/2019',6),('4/1/2019',5);
-- Sortless Grouping/Ordering/Aggregating without an Index (or Hashing)
SELECT
MonthOfYear = DATEADD(DAY,-(DAY(MAX(Dt))-1),MAX(Dt)),
Sales = SUM(Sales)
FROM (SELECT startdate = MIN(t.ReportDate), enddate = MAX(t.ReportDate) FROM @table AS t) AS D
CROSS APPLY
(
SELECT
MonthId = r.RN,
Dt = dt.D,
Yr = YEAR(dt.D),
Mo = MONTH(dt.D)
FROM (VALUES(DATEDIFF(MONTH,D.startdate,D.enddate))) AS f(DD)
CROSS APPLY dbo.rangeAB(0,ABS(f.DD),1,0) AS r
CROSS APPLY (VALUES(DATEADD(MONTH,r.RN*SIGN(f.DD),D.startdate))) AS dt(D)
) AS f
JOIN @table AS t ON f.Mo = MONTH(t.ReportDate) AND f.Yr = YEAR(t.ReportDate)
GROUP BY f.MonthId
ORDER BY f.MonthId;
Returns:
MonthOfYear Sales
----------- -----------
2018-11-01 4
2019-03-01 8
2019-04-01 5
...和执行计划：
看马^^^ 不怎么样！
RangeAB DDL:
CREATE FUNCTION dbo.rangeAB
(
@low bigint,
@high bigint,
@gap bigint,
@row1 bit
)
/****************************************************************************************
[Purpose]:
Creates up to 531,441,000,000 sequentia1 integers numbers beginning with @low and ending
with @high. Used to replace iterative methods such as loops, cursors and recursive CTEs
to solve SQL problems. Based on Itzik Ben-Gan's getnums function with some tweeks and
enhancements and added functionality. The logic for getting rn to begin at 0 or 1 is
based comes from Jeff Moden's fnTally function.
The name range because it's similar to clojure's range function. The name "rangeAB" as
used because "range" is a reserved SQL keyword.
[Author]: Alan Burstein
[Compatibility]:
SQL Server 2008+ and Azure SQL Database
[Syntax]:
SELECT r.RN, r.OP, r.N1, r.N2
FROM dbo.rangeAB(@low,@high,@gap,@row1) AS r;
[Parameters]:
@low = a bigint that represents the lowest value for n1.
@high = a bigint that represents the highest value for n1.
@gap = a bigint that represents how much n1 and n2 will increase each row; @gap also
represents the difference between n1 and n2.
@row1 = a bit that represents the first value of rn. When @row = 0 then rn begins
at 0, when @row = 1 then rn will begin at 1.
[Returns]:
Inline Table Valued Function returns:
rn = bigint; a row number that works just like T-SQL ROW_NUMBER() except that it can
start at 0 or 1 which is dictated by @row1.
op = bigint; returns the "opposite number that relates to rn. When rn begins with 0 and
ends with 10 then 10 is the opposite of 0, 9 the opposite of 1, etc. When rn begins
with 1 and ends with 5 then 1 is the opposite of 5, 2 the opposite of 4, etc...
n1 = bigint; a sequential number starting at the value of @low and incrimentingby the
value of @gap until it is less than or equal to the value of @high.
n2 = bigint; a sequential number starting at the value of @low+@gap and incrimenting
by the value of @gap.
[Dependencies]:
N/A
[Developer Notes]:
1. The lowest and highest possible numbers returned are whatever is allowable by a
bigint. The function, however, returns no more than 531,441,000,000 rows (8100^3).
2. @gap does not affect rn, rn will begin at @row1 and increase by 1 until the last row
unless its used in a query where a filter is applied to rn.
3. @gap must be greater than 0 or the function will not return any rows.
4. Keep in mind that when @row1 is 0 then the highest row-number will be the number of
rows returned minus 1
5. If you only need is a sequential set beginning at 0 or 1 then, for best performance
use the RN column. Use N1 and/or N2 when you need to begin your sequence at any
number other than 0 or 1 or if you need a gap between your sequence of numbers.
6. Although @gap is a bigint it must be a positive integer or the function will
not return any rows.
7. The function will not return any rows when one of the following conditions are true:
* any of the input parameters are NULL
* @high is less than @low
* @gap is not greater than 0
To force the function to return all NULLs instead of not returning anything you can
add the following code to the end of the query:
UNION ALL
SELECT NULL, NULL, NULL, NULL
WHERE NOT (@high&@low&@gap&@row1 IS NOT NULL AND @high >= @low AND @gap > 0)
This code was excluded as it adds a ~5% performance penalty.
8. There is no performance penalty for sorting by rn ASC; there is a large performance
penalty for sorting in descending order WHEN @row1 = 1; WHEN @row1 = 0
If you need a descending sort the use op in place of rn then sort by rn ASC.
Best Practices:
--===== 1. Using RN (rownumber)
-- (1.1) The best way to get the numbers 1,2,3...@high (e.g. 1 to 5):
SELECT RN FROM dbo.rangeAB(1,5,1,1);
-- (1.2) The best way to get the numbers 0,1,2...@high-1 (e.g. 0 to 5):
SELECT RN FROM dbo.rangeAB(0,5,1,0);
--===== 2. Using OP for descending sorts without a performance penalty
-- (2.1) The best way to get the numbers 5,4,3...@high (e.g. 5 to 1):
SELECT op FROM dbo.rangeAB(1,5,1,1) ORDER BY rn ASC;
-- (2.2) The best way to get the numbers 0,1,2...@high-1 (e.g. 5 to 0):
SELECT op FROM dbo.rangeAB(1,6,1,0) ORDER BY rn ASC;
--===== 3. Using N1
-- (3.1) To begin with numbers other than 0 or 1 use N1 (e.g. -3 to 3):
SELECT N1 FROM dbo.rangeAB(-3,3,1,1);
-- (3.2) ROW_NUMBER() is built in. If you want a ROW_NUMBER() include RN:
SELECT RN, N1 FROM dbo.rangeAB(-3,3,1,1);
-- (3.3) If you wanted a ROW_NUMBER() that started at 0 you would do this:
SELECT RN, N1 FROM dbo.rangeAB(-3,3,1,0);
--===== 4. Using N2 and @gap
-- (4.1) To get 0,10,20,30...100, set @low to 0, @high to 100 and @gap to 10:
SELECT N1 FROM dbo.rangeAB(0,100,10,1);
-- (4.2) Note that N2=N1+@gap; this allows you to create a sequence of ranges.
-- For example, to get (0,10),(10,20),(20,30).... (90,100):
SELECT N1, N2 FROM dbo.rangeAB(0,90,10,1);
-- (4.3) Remember that a rownumber is included and it can begin at 0 or 1:
SELECT RN, N1, N2 FROM dbo.rangeAB(0,90,10,1);
[Examples]:
--===== 1. Generating Sample data (using rangeAB to create "dummy rows")
-- The query below will generate 10,000 ids and random numbers between 50,000 and 500,000
SELECT
someId = r.rn,
someNumer = ABS(CHECKSUM(NEWID())%450000)+50001
FROM rangeAB(1,10000,1,1) r;
--===== 2. Create a series of dates; rn is 0 to include the first date in the series
DECLARE @startdate DATE = '20180101', @enddate DATE = '20180131';
SELECT r.rn, calDate = DATEADD(dd, r.rn, @startdate)
FROM dbo.rangeAB(1, DATEDIFF(dd,@startdate,@enddate),1,0) r;
GO
--===== 3. Splitting (tokenizing) a string with fixed sized items
-- given a delimited string of identifiers that are always 7 characters long
DECLARE @string VARCHAR(1000) = 'A601225,B435223,G008081,R678567';
SELECT
itemNumber = r.rn, -- item's ordinal position
itemIndex = r.n1, -- item's position in the string (it's CHARINDEX value)
item = SUBSTRING(@string, r.n1, 7) -- item (token)
FROM dbo.rangeAB(1, LEN(@string), 8,1) r;
GO
--===== 4. Splitting (tokenizing) a string with random delimiters
DECLARE @string VARCHAR(1000) = 'ABC123,999F,XX,9994443335';
SELECT
itemNumber = ROW_NUMBER() OVER (ORDER BY r.rn), -- item's ordinal position
itemIndex = r.n1+1, -- item's position in the string (it's CHARINDEX value)
item = SUBSTRING
(
@string,
r.n1+1,
ISNULL(NULLIF(CHARINDEX(',',@string,r.n1+1),0)-r.n1-1, 8000)
) -- item (token)
FROM dbo.rangeAB(0,DATALENGTH(@string),1,1) r
WHERE SUBSTRING(@string,r.n1,1) = ',' OR r.n1 = 0;
-- logic borrowed from: http://www.sqlservercentral.com/articles/Tally+Table/72993/
--===== 5. Grouping by a weekly intervals
-- 5.1. how to create a series of start/end dates between @startDate & @endDate
DECLARE @startDate DATE = '1/1/2015', @endDate DATE = '2/1/2015';
SELECT
WeekNbr = r.RN,
WeekStart = DATEADD(DAY,r.N1,@StartDate),
WeekEnd = DATEADD(DAY,r.N2-1,@StartDate)
FROM dbo.rangeAB(0,datediff(DAY,@StartDate,@EndDate),7,1) r;
GO
-- 5.2. LEFT JOIN to the weekly interval table
BEGIN
DECLARE @startDate datetime = '1/1/2015', @endDate datetime = '2/1/2015';
-- sample data
DECLARE @loans TABLE (loID INT, lockDate DATE);
INSERT @loans SELECT r.rn, DATEADD(dd, ABS(CHECKSUM(NEWID())%32), @startDate)
FROM dbo.rangeAB(1,50,1,1) r;
-- solution
SELECT
WeekNbr = r.RN,
WeekStart = dt.WeekStart,
WeekEnd = dt.WeekEnd,
total = COUNT(l.lockDate)
FROM dbo.rangeAB(0,datediff(DAY,@StartDate,@EndDate),7,1) r
CROSS APPLY (VALUES (
CAST(DATEADD(DAY,r.N1,@StartDate) AS DATE),
CAST(DATEADD(DAY,r.N2-1,@StartDate) AS DATE))) dt(WeekStart,WeekEnd)
LEFT JOIN @loans l ON l.lockDate BETWEEN dt.WeekStart AND dt.WeekEnd
GROUP BY r.RN, dt.WeekStart, dt.WeekEnd ;
END;
--===== 6. Identify the first vowel and last vowel in a along with their positions
DECLARE @string VARCHAR(200) = 'This string has vowels';
SELECT TOP(1) position = r.rn, letter = SUBSTRING(@string,r.rn,1)
FROM dbo.rangeAB(1,LEN(@string),1,1) r
WHERE SUBSTRING(@string,r.rn,1) LIKE '%[aeiou]%'
ORDER BY r.rn;
-- To avoid a sort in the execution plan we'll use op instead of rn
SELECT TOP(1) position = r.op, letter = SUBSTRING(@string,r.op,1)
FROM dbo.rangeAB(1,LEN(@string),1,1) r
WHERE SUBSTRING(@string,r.rn,1) LIKE '%[aeiou]%'
ORDER BY r.rn;
---------------------------------------------------------------------------------------
[Revision History]:
Rev 00 - 20140518 - Initial Development - Alan Burstein
Rev 01 - 20151029 - Added 65 rows to make L1=465; 465^3=100.5M. Updated comment section
- Alan Burstein
Rev 02 - 20180613 - Complete re-design including opposite number column (op)
Rev 03 - 20180920 - Added additional CROSS JOIN to L2 for 530B rows max - Alan Burstein
****************************************************************************************/
RETURNS TABLE WITH SCHEMABINDING AS RETURN
WITH L1(N) AS
(
SELECT 1
FROM (VALUES
(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),
(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),
(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),
(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),
(0),(0)) T(N) -- 90 values
),
L2(N) AS (SELECT 1 FROM L1 a CROSS JOIN L1 b CROSS JOIN L1 c),
iTally AS (SELECT rn = ROW_NUMBER() OVER (ORDER BY (SELECT 1)) FROM L2 a CROSS JOIN L2 b)
SELECT
r.RN,
r.OP,
r.N1,
r.N2
FROM
(
SELECT
RN = 0,
OP = (@high-@low)/@gap,
N1 = @low,
N2 = @gap+@low
WHERE @row1 = 0
UNION ALL -- ISNULL required in the TOP statement below for error handling purposes
SELECT TOP (ABS((ISNULL(@high,0)-ISNULL(@low,0))/ISNULL(@gap,0)+ISNULL(@row1,1)))
RN = i.rn,
OP = (@high-@low)/@gap+(2*@row1)-i.rn,
N1 = (i.rn-@row1)*@gap+@low,
N2 = (i.rn-(@row1-1))*@gap+@low
FROM iTally AS i
ORDER BY i.rn
) AS r
WHERE @high&@low&@gap&@row1 IS NOT NULL AND @high >= @low AND @gap > 0;
GO
我按月对数据进行分组，结果应该是 Date.
我发布的示例目前有效，但我发现它太长太笨拙，因为我必须解析最终日期以用作分组。
无论如何，这是整个脚本：
declare @table table
(
ReportDate date,
Sales int
)
insert into @table
select '11/5/2018', 1 union
select '11/8/2018', 3 union
select '3/5/2019', 2 union
select '3/8/2019', 6 union
select '4/1/2019', 5
select
cast(CAST(MONTH(reportdate) AS VARCHAR(2)) + '/1/' + CAST(year(reportdate) AS VARCHAR(4)) as date) as 'MonthOfYear',
SUM(sales) as 'sales' FROM @table
group by
cast(CAST(MONTH(reportdate) AS VARCHAR(2)) + '/1/' + CAST(year(reportdate) AS VARCHAR(4)) as date)
order by cast(CAST(MONTH(reportdate) AS VARCHAR(2)) + '/1/' + CAST(year(reportdate) AS VARCHAR(4)) as date)
哪个returns:
MonthOfYear sales
2018-11-01 4
2019-03-01 8
2019-04-01 5
结果是正确的，但我觉得这很笨拙而且很长。是否有更紧凑的按月分组的方法，其中结果的类型为 Date?
我假设你在寻找格式：
DECLARE @d DATETIME = '10/01/2011';
SELECT FORMAT ( @d, 'd', 'en-US' ) AS 'US English Result'
,FORMAT ( @d, 'd', 'en-gb' ) AS 'Great Britain English Result'
,FORMAT ( @d, 'd', 'de-de' ) AS 'German Result'
,FORMAT ( @d, 'd', 'zh-cn' ) AS 'Simplified Chinese (PRC) Result';
SELECT FORMAT ( @d, 'D', 'en-US' ) AS 'US English Result'
,FORMAT ( @d, 'D', 'en-gb' ) AS 'Great Britain English Result'
,FORMAT ( @d, 'D', 'de-de' ) AS 'German Result'
,FORMAT ( @d, 'D', 'zh-cn' ) AS 'Chinese (Simplified PRC) Result';
更多详情： https://docs.microsoft.com/en-us/sql/t-sql/functions/format-transact-sql?view=sql-server-ver15
结果：
将日期更改为 2008 年月初的常用方法是使用 DATEADD 和 DATEDIFF 来代替日期 0（又名 19000101）：
SELECT CONVERT(date,DATEADD(MONTH,DATEDIFF(MONTH,0,T.ReportDate),0)) AS MonthDate,
SUM(Sales) AS TotalSales
FROM @table T
GROUP BY DATEADD(MONTH,DATEDIFF(MONTH,0,T.ReportDate),0);
如果您使用的是 2012+（您确实应该使用 2008，现在 完全 不受支持），您可以使用 EOMONTH 和 DATEADD:
SELECT DATEADD(DAY, 1, EOMONTH(T.ReportDate,-1)) AS MonthDate,
SUM(Sales) AS TotalSales
FROM @table T
GROUP BY DATEADD(DAY, 1, EOMONTH(T.ReportDate,-1));
这样做的好处是不必将 CAST/CONVERT 表达式返回到 date（因为 0 或 '19000101' 会被解释为作为 datetime).
有用的提示。提供日期时，请避免使用模棱两可的格式。我得到的结果与您的预期结果 不 相同，因为像 '11/5/2018' 这样的日期意味着 2018 年 5 月 11 日。考虑到您的所有日期在 d/M/yyyy 和 M/d/yyyy 格式，这使得它更加混乱。当为 SQL 服务器问题提供日期时，yyyyMMdd 和 yyyy-MM-DDThh:mm:ss.nnnnnnn 是最好的格式，因为它们没有歧义。
+'-01'可选
Select MonthOfYear = convert(varchar(7),ReportDate,120)+'-01'
,Sales = sum(Sales)
From @table
Group BY convert(varchar(7),ReportDate,120)
Returns
MonthOfYear Sales
2018-11-01 4
2019-03-01 8
2019-04-01 5
EDIT
而不是 convert()，您可以使用隐式转换并使用
left(ReportDate,7)
如果您使用 Calendar table，基于日期的报告变得 很多 更容易和更快。日历 table 包含下一个（例如 50 年）所有日期的条目，具有年、季度、学期、月、月中日、年中日、星期几、周数等的明确列。Date 是主键，其余列根据报告需要编制索引。
假设您创建一个 table，每个日期的 StartOfMonth 都有一个额外的列，查询可以变得像这样简单：
SELECT StartOfMonth,sum(Sales)
FROM @table inner join Calendar on Calendar.Date=ReportDate
GROUP BY StartOfMonth
select cast(yyyymm + '01' as date) as MonthOfYear,
SUM(sales) as sales
from @table cross apply (select convert(char(6),ReportDate, 112) as yyyymm)a
group by yyyymm
order by MonthOfYear;
我会看看@Panagiotis Kanavos 的日历 Table 并给你一个 虚拟索引。使用 rangeAB（下面的 DDL），您可以 group/sort/Aggregate/order/de-duplicate/etc 而无需创建索引 .
-- Your data (no index)
declare @table table
(
ReportDate date,
Sales int
)
insert @table VALUES ('11/5/2018',1),('11/8/2018',3),('3/5/2019',2),('3/8/2019',6),('4/1/2019',5);
-- Sortless Grouping/Ordering/Aggregating without an Index (or Hashing)
SELECT
MonthOfYear = DATEADD(DAY,-(DAY(MAX(Dt))-1),MAX(Dt)),
Sales = SUM(Sales)
FROM (SELECT startdate = MIN(t.ReportDate), enddate = MAX(t.ReportDate) FROM @table AS t) AS D
CROSS APPLY
(
SELECT
MonthId = r.RN,
Dt = dt.D,
Yr = YEAR(dt.D),
Mo = MONTH(dt.D)
FROM (VALUES(DATEDIFF(MONTH,D.startdate,D.enddate))) AS f(DD)
CROSS APPLY dbo.rangeAB(0,ABS(f.DD),1,0) AS r
CROSS APPLY (VALUES(DATEADD(MONTH,r.RN*SIGN(f.DD),D.startdate))) AS dt(D)
) AS f
JOIN @table AS t ON f.Mo = MONTH(t.ReportDate) AND f.Yr = YEAR(t.ReportDate)
GROUP BY f.MonthId
ORDER BY f.MonthId;
Returns:
MonthOfYear Sales
----------- -----------
2018-11-01 4
2019-03-01 8
2019-04-01 5
...和执行计划：
RangeAB DDL:
CREATE FUNCTION dbo.rangeAB
(
@low bigint,
@high bigint,
@gap bigint,
@row1 bit
)
/****************************************************************************************
[Purpose]:
Creates up to 531,441,000,000 sequentia1 integers numbers beginning with @low and ending
with @high. Used to replace iterative methods such as loops, cursors and recursive CTEs
to solve SQL problems. Based on Itzik Ben-Gan's getnums function with some tweeks and
enhancements and added functionality. The logic for getting rn to begin at 0 or 1 is
based comes from Jeff Moden's fnTally function.
The name range because it's similar to clojure's range function. The name "rangeAB" as
used because "range" is a reserved SQL keyword.
[Author]: Alan Burstein
[Compatibility]:
SQL Server 2008+ and Azure SQL Database
[Syntax]:
SELECT r.RN, r.OP, r.N1, r.N2
FROM dbo.rangeAB(@low,@high,@gap,@row1) AS r;
[Parameters]:
@low = a bigint that represents the lowest value for n1.
@high = a bigint that represents the highest value for n1.
@gap = a bigint that represents how much n1 and n2 will increase each row; @gap also
represents the difference between n1 and n2.
@row1 = a bit that represents the first value of rn. When @row = 0 then rn begins
at 0, when @row = 1 then rn will begin at 1.
[Returns]:
Inline Table Valued Function returns:
rn = bigint; a row number that works just like T-SQL ROW_NUMBER() except that it can
start at 0 or 1 which is dictated by @row1.
op = bigint; returns the "opposite number that relates to rn. When rn begins with 0 and
ends with 10 then 10 is the opposite of 0, 9 the opposite of 1, etc. When rn begins
with 1 and ends with 5 then 1 is the opposite of 5, 2 the opposite of 4, etc...
n1 = bigint; a sequential number starting at the value of @low and incrimentingby the
value of @gap until it is less than or equal to the value of @high.
n2 = bigint; a sequential number starting at the value of @low+@gap and incrimenting
by the value of @gap.
[Dependencies]:
N/A
[Developer Notes]:
1. The lowest and highest possible numbers returned are whatever is allowable by a
bigint. The function, however, returns no more than 531,441,000,000 rows (8100^3).
2. @gap does not affect rn, rn will begin at @row1 and increase by 1 until the last row
unless its used in a query where a filter is applied to rn.
3. @gap must be greater than 0 or the function will not return any rows.
4. Keep in mind that when @row1 is 0 then the highest row-number will be the number of
rows returned minus 1
5. If you only need is a sequential set beginning at 0 or 1 then, for best performance
use the RN column. Use N1 and/or N2 when you need to begin your sequence at any
number other than 0 or 1 or if you need a gap between your sequence of numbers.
6. Although @gap is a bigint it must be a positive integer or the function will
not return any rows.
7. The function will not return any rows when one of the following conditions are true:
* any of the input parameters are NULL
* @high is less than @low
* @gap is not greater than 0
To force the function to return all NULLs instead of not returning anything you can
add the following code to the end of the query:
UNION ALL
SELECT NULL, NULL, NULL, NULL
WHERE NOT (@high&@low&@gap&@row1 IS NOT NULL AND @high >= @low AND @gap > 0)
This code was excluded as it adds a ~5% performance penalty.
8. There is no performance penalty for sorting by rn ASC; there is a large performance
penalty for sorting in descending order WHEN @row1 = 1; WHEN @row1 = 0
If you need a descending sort the use op in place of rn then sort by rn ASC.
Best Practices:
--===== 1. Using RN (rownumber)
-- (1.1) The best way to get the numbers 1,2,3...@high (e.g. 1 to 5):
SELECT RN FROM dbo.rangeAB(1,5,1,1);
-- (1.2) The best way to get the numbers 0,1,2...@high-1 (e.g. 0 to 5):
SELECT RN FROM dbo.rangeAB(0,5,1,0);
--===== 2. Using OP for descending sorts without a performance penalty
-- (2.1) The best way to get the numbers 5,4,3...@high (e.g. 5 to 1):
SELECT op FROM dbo.rangeAB(1,5,1,1) ORDER BY rn ASC;
-- (2.2) The best way to get the numbers 0,1,2...@high-1 (e.g. 5 to 0):
SELECT op FROM dbo.rangeAB(1,6,1,0) ORDER BY rn ASC;
--===== 3. Using N1
-- (3.1) To begin with numbers other than 0 or 1 use N1 (e.g. -3 to 3):
SELECT N1 FROM dbo.rangeAB(-3,3,1,1);
-- (3.2) ROW_NUMBER() is built in. If you want a ROW_NUMBER() include RN:
SELECT RN, N1 FROM dbo.rangeAB(-3,3,1,1);
-- (3.3) If you wanted a ROW_NUMBER() that started at 0 you would do this:
SELECT RN, N1 FROM dbo.rangeAB(-3,3,1,0);
--===== 4. Using N2 and @gap
-- (4.1) To get 0,10,20,30...100, set @low to 0, @high to 100 and @gap to 10:
SELECT N1 FROM dbo.rangeAB(0,100,10,1);
-- (4.2) Note that N2=N1+@gap; this allows you to create a sequence of ranges.
-- For example, to get (0,10),(10,20),(20,30).... (90,100):
SELECT N1, N2 FROM dbo.rangeAB(0,90,10,1);
-- (4.3) Remember that a rownumber is included and it can begin at 0 or 1:
SELECT RN, N1, N2 FROM dbo.rangeAB(0,90,10,1);
[Examples]:
--===== 1. Generating Sample data (using rangeAB to create "dummy rows")
-- The query below will generate 10,000 ids and random numbers between 50,000 and 500,000
SELECT
someId = r.rn,
someNumer = ABS(CHECKSUM(NEWID())%450000)+50001
FROM rangeAB(1,10000,1,1) r;
--===== 2. Create a series of dates; rn is 0 to include the first date in the series
DECLARE @startdate DATE = '20180101', @enddate DATE = '20180131';
SELECT r.rn, calDate = DATEADD(dd, r.rn, @startdate)
FROM dbo.rangeAB(1, DATEDIFF(dd,@startdate,@enddate),1,0) r;
GO
--===== 3. Splitting (tokenizing) a string with fixed sized items
-- given a delimited string of identifiers that are always 7 characters long
DECLARE @string VARCHAR(1000) = 'A601225,B435223,G008081,R678567';
SELECT
itemNumber = r.rn, -- item's ordinal position
itemIndex = r.n1, -- item's position in the string (it's CHARINDEX value)
item = SUBSTRING(@string, r.n1, 7) -- item (token)
FROM dbo.rangeAB(1, LEN(@string), 8,1) r;
GO
--===== 4. Splitting (tokenizing) a string with random delimiters
DECLARE @string VARCHAR(1000) = 'ABC123,999F,XX,9994443335';
SELECT
itemNumber = ROW_NUMBER() OVER (ORDER BY r.rn), -- item's ordinal position
itemIndex = r.n1+1, -- item's position in the string (it's CHARINDEX value)
item = SUBSTRING
(
@string,
r.n1+1,
ISNULL(NULLIF(CHARINDEX(',',@string,r.n1+1),0)-r.n1-1, 8000)
) -- item (token)
FROM dbo.rangeAB(0,DATALENGTH(@string),1,1) r
WHERE SUBSTRING(@string,r.n1,1) = ',' OR r.n1 = 0;
-- logic borrowed from: http://www.sqlservercentral.com/articles/Tally+Table/72993/
--===== 5. Grouping by a weekly intervals
-- 5.1. how to create a series of start/end dates between @startDate & @endDate
DECLARE @startDate DATE = '1/1/2015', @endDate DATE = '2/1/2015';
SELECT
WeekNbr = r.RN,
WeekStart = DATEADD(DAY,r.N1,@StartDate),
WeekEnd = DATEADD(DAY,r.N2-1,@StartDate)
FROM dbo.rangeAB(0,datediff(DAY,@StartDate,@EndDate),7,1) r;
GO
-- 5.2. LEFT JOIN to the weekly interval table
BEGIN
DECLARE @startDate datetime = '1/1/2015', @endDate datetime = '2/1/2015';
-- sample data
DECLARE @loans TABLE (loID INT, lockDate DATE);
INSERT @loans SELECT r.rn, DATEADD(dd, ABS(CHECKSUM(NEWID())%32), @startDate)
FROM dbo.rangeAB(1,50,1,1) r;
-- solution
SELECT
WeekNbr = r.RN,
WeekStart = dt.WeekStart,
WeekEnd = dt.WeekEnd,
total = COUNT(l.lockDate)
FROM dbo.rangeAB(0,datediff(DAY,@StartDate,@EndDate),7,1) r
CROSS APPLY (VALUES (
CAST(DATEADD(DAY,r.N1,@StartDate) AS DATE),
CAST(DATEADD(DAY,r.N2-1,@StartDate) AS DATE))) dt(WeekStart,WeekEnd)
LEFT JOIN @loans l ON l.lockDate BETWEEN dt.WeekStart AND dt.WeekEnd
GROUP BY r.RN, dt.WeekStart, dt.WeekEnd ;
END;
--===== 6. Identify the first vowel and last vowel in a along with their positions
DECLARE @string VARCHAR(200) = 'This string has vowels';
SELECT TOP(1) position = r.rn, letter = SUBSTRING(@string,r.rn,1)
FROM dbo.rangeAB(1,LEN(@string),1,1) r
WHERE SUBSTRING(@string,r.rn,1) LIKE '%[aeiou]%'
ORDER BY r.rn;
-- To avoid a sort in the execution plan we'll use op instead of rn
SELECT TOP(1) position = r.op, letter = SUBSTRING(@string,r.op,1)
FROM dbo.rangeAB(1,LEN(@string),1,1) r
WHERE SUBSTRING(@string,r.rn,1) LIKE '%[aeiou]%'
ORDER BY r.rn;
---------------------------------------------------------------------------------------
[Revision History]:
Rev 00 - 20140518 - Initial Development - Alan Burstein
Rev 01 - 20151029 - Added 65 rows to make L1=465; 465^3=100.5M. Updated comment section
- Alan Burstein
Rev 02 - 20180613 - Complete re-design including opposite number column (op)
Rev 03 - 20180920 - Added additional CROSS JOIN to L2 for 530B rows max - Alan Burstein
****************************************************************************************/
RETURNS TABLE WITH SCHEMABINDING AS RETURN
WITH L1(N) AS
(
SELECT 1
FROM (VALUES
(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),
(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),
(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),
(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),(0),
(0),(0)) T(N) -- 90 values
),
L2(N) AS (SELECT 1 FROM L1 a CROSS JOIN L1 b CROSS JOIN L1 c),
iTally AS (SELECT rn = ROW_NUMBER() OVER (ORDER BY (SELECT 1)) FROM L2 a CROSS JOIN L2 b)
SELECT
r.RN,
r.OP,
r.N1,
r.N2
FROM
(
SELECT
RN = 0,
OP = (@high-@low)/@gap,
N1 = @low,
N2 = @gap+@low
WHERE @row1 = 0
UNION ALL -- ISNULL required in the TOP statement below for error handling purposes
SELECT TOP (ABS((ISNULL(@high,0)-ISNULL(@low,0))/ISNULL(@gap,0)+ISNULL(@row1,1)))
RN = i.rn,
OP = (@high-@low)/@gap+(2*@row1)-i.rn,
N1 = (i.rn-@row1)*@gap+@low,
N2 = (i.rn-(@row1-1))*@gap+@low
FROM iTally AS i
ORDER BY i.rn
) AS r
WHERE @high&@low&@gap&@row1 IS NOT NULL AND @high >= @low AND @gap > 0;
GO