SQL query for counting records per month(用于计算每月记录的 SQL 查询)
本文介绍了用于计算每月记录的 SQL 查询的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个数据集，需要为特定用户的每月访问次数构建.我有一个包含以下字段的 SQL 表:
I have a dataset I need to build for number of visits per month for particular user. I have a SQL table which contains these fields:
- 用户 nvarchar(30)
- 日期访问日期时间
- User nvarchar(30)
- DateVisit datetime
我现在想要实现的是将每个用户的所有访问按月分组，如图所示:
What I want to achieve now is to get all the visits grouped by month for each user, something like at the picture:
我开始查询，我可以通过这个查询获得月份和该月的总访问量(不按用户拆分)；
I started the query, I am able to get the months and the total sum of visits for that month (not split by user) with this query;
select [1] AS January,
[2] AS February,
[3] AS March,
[4] AS April,
[5] AS May,
[6] AS June,
[7] AS July,
[8] AS August,
[9] AS September,
[10] AS October,
[11] AS November,
[12] AS December
from
(
SELECT MONTH(DateVisit) AS month, [User] FROM UserVisit
) AS t
PIVOT (
COUNT([User])
FOR month IN([1], [2], [3], [4], [5],[6],[7],[8],[9],[10],[11],[12])
) p
通过上面的查询，我得到了这个结果:
With the query above I am getting this result:
现在我想知道如何为用户再添加一列并按用户拆分值.
Now I want to know how I can add one more column for user and split the values by user.
推荐答案
好的，两种解决方案看起来都不错.Ali 的答案有效，但我会改用 SUM() 函数，我讨厌 NULLS.让我们同时尝试一下，看看查询计划与执行时间的对比.
Okay, both solutions look good. The answer by Ali works but I would use a SUM() function instead, I hate NULLS. Let's try both and see the query plans versus execution times.
我总是用数据创建一个测试表，这样我就不会给用户 Aziale 错误的答案.
I always create a test table with data so that I do not give the user, Aziale, bad answers.
下面的代码不是最漂亮的，但它确实设置了一个测试用例.我在 tempdb 中创建了一个名为 user_visits 的数据库.对于每个月，我使用 for 循环添加用户并为他们提供该月的创建开始日期.
The code below is not the prettiest but it does set up a test case. I made a database in tempdb called user_visits. For each month, I used a for loop to add the users and give them the create start date for the month.
现在我们有了数据，我们可以玩了.
Now that we have data, we can play.
-- Drop the table
drop table tempdb.dbo.user_visits
go
-- Create the table
create table tempdb.dbo.user_visits
(
uv_id int identity(1, 1),
uv_visit_date smalldatetime,
uv_user_name varchar(30)
);
go
-- January data
declare @cnt int = 1;
while @cnt <= 103
begin
if (@cnt <= 21)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130101', 'Patrick');
if (@cnt <= 44)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130101', 'Barbara');
if (@cnt <= 65)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130101', 'Danielle');
if (@cnt <= 103)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130101', 'John');
set @cnt = @cnt + 1
end
go
-- February data
declare @cnt int = 1;
while @cnt <= 99
begin
if (@cnt <= 29)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130201', 'Patrick');
if (@cnt <= 42)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130201', 'Barbara');
if (@cnt <= 55)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130201', 'Danielle');
if (@cnt <= 99)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130201', 'John');
set @cnt = @cnt + 1
end
go
-- March data
declare @cnt int = 1;
while @cnt <= 98
begin
if (@cnt <= 25)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130301', 'Patrick');
if (@cnt <= 46)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130301', 'Barbara');
if (@cnt <= 75)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130301', 'Danielle');
if (@cnt <= 98)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130301', 'John');
set @cnt = @cnt + 1
end
go
-- April data
declare @cnt int = 1;
while @cnt <= 91
begin
if (@cnt <= 32)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130401', 'Patrick');
if (@cnt <= 48)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130401', 'Barbara');
if (@cnt <= 60)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130401', 'Danielle');
if (@cnt <= 91)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130401', 'John');
set @cnt = @cnt + 1
end
go
-- May data
declare @cnt int = 1;
while @cnt <= 120
begin
if (@cnt <= 40)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130501', 'Patrick');
if (@cnt <= 41)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130501', 'Barbara');
if (@cnt <= 70)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130501', 'Danielle');
if (@cnt <= 120)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130501', 'John');
set @cnt = @cnt + 1
end
go
-- June data
declare @cnt int = 1;
while @cnt <= 103
begin
if (@cnt <= 17)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130601', 'Patrick');
if (@cnt <= 45)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130601', 'Barbara');
if (@cnt <= 62)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130601', 'Danielle');
if (@cnt <= 103)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130601', 'John');
set @cnt = @cnt + 1
end
go
-- July data
declare @cnt int = 1;
while @cnt <= 99
begin
if (@cnt <= 20)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130701', 'Patrick');
if (@cnt <= 43)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130701', 'Barbara');
if (@cnt <= 66)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130701', 'Danielle');
if (@cnt <= 99)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130701', 'John');
set @cnt = @cnt + 1
end
go
-- August data
declare @cnt int = 1;
while @cnt <= 98
begin
if (@cnt <= 26)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130801', 'Patrick');
if (@cnt <= 47)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130801', 'Barbara');
if (@cnt <= 71)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130801', 'Danielle');
if (@cnt <= 98)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130801', 'John');
set @cnt = @cnt + 1
end
go
-- September data
declare @cnt int = 1;
while @cnt <= 91
begin
if (@cnt <= 25)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130901', 'Patrick');
if (@cnt <= 49)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130901', 'Barbara');
if (@cnt <= 59)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130901', 'Danielle');
if (@cnt <= 91)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20130901', 'John');
set @cnt = @cnt + 1
end
go
-- October data
declare @cnt int = 1;
while @cnt <= 120
begin
if (@cnt <= 25)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131001', 'Patrick');
if (@cnt <= 40)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131001', 'Barbara');
if (@cnt <= 73)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131001', 'Danielle');
if (@cnt <= 120)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131001', 'John');
set @cnt = @cnt + 1
end
go
-- November data
declare @cnt int = 1;
while @cnt <= 101
begin
if (@cnt <= 32)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131101', 'Patrick');
if (@cnt <= 50)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131101', 'Barbara');
if (@cnt <= 65)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131101', 'Danielle');
if (@cnt <= 101)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131101', 'John');
set @cnt = @cnt + 1
end
go
-- December data
declare @cnt int = 1;
while @cnt <= 90
begin
if (@cnt <= 40)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131201', 'Patrick');
if (@cnt <= 52)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131201', 'Barbara');
if (@cnt <= 61)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131201', 'Danielle');
if (@cnt <= 90)
insert into tempdb.dbo.user_visits
(uv_visit_date, uv_user_name)
values ('20131201', 'John');
set @cnt = @cnt + 1
end
go
请不要在编码中使用保留字作为列名 - IE - 月份是保留字.
Please do not use reserve words in coding as column names - IE - month is a reserve word.
下面的代码给你正确的答案.
The code below gives you the correct answer.
-- Grab the data (1)
select
my_user,
[1] AS January,
[2] AS Febrary,
[3] AS March,
[4] AS April,
[5] AS May,
[6] AS June,
[7] AS July,
[8] AS August,
[9] AS September,
[10] AS October,
[11] AS November,
[12] AS December
from
(
SELECT MONTH(uv_visit_date) AS my_month, uv_user_name as my_user FROM tempdb.dbo.user_visits
) AS t
PIVOT (
COUNT(my_month)
FOR my_month IN([1], [2], [3], [4], [5],[6],[7],[8],[9],[10],[11],[12])
) as p
-- Grab the data (2)
SELECT uv_user_name
, SUM(CASE WHEN MONTH(uv_visit_date) = 1 THEN 1 ELSE 0 END) January
, SUM(CASE WHEN MONTH(uv_visit_date) = 2 THEN 1 ELSE 0 END) Feburary
, SUM(CASE WHEN MONTH(uv_visit_date) = 3 THEN 1 ELSE 0 END) March
, SUM(CASE WHEN MONTH(uv_visit_date) = 4 THEN 1 ELSE 0 END) April
, SUM(CASE WHEN MONTH(uv_visit_date) = 5 THEN 1 ELSE 0 END) May
, SUM(CASE WHEN MONTH(uv_visit_date) = 6 THEN 1 ELSE 0 END) June
, SUM(CASE WHEN MONTH(uv_visit_date) = 7 THEN 1 ELSE 0 END) July
, SUM(CASE WHEN MONTH(uv_visit_date) = 8 THEN 1 ELSE 0 END) August
, SUM(CASE WHEN MONTH(uv_visit_date) = 9 THEN 1 ELSE 0 END) September
, SUM(CASE WHEN MONTH(uv_visit_date) = 10 THEN 1 ELSE 0 END) October
, SUM(CASE WHEN MONTH(uv_visit_date) = 11 THEN 1 ELSE 0 END) November
, SUM(CASE WHEN MONTH(uv_visit_date) = 12 THEN 1 ELSE 0 END) December
FROM tempdb.dbo.user_visits
GROUP BY uv_user_name
进行此类分析时，请始终清除缓存/缓冲区并获取 I/O.
When doing this type of analysis, always clear the cache/buffers and get the I/O.
-- Show time & i/o
SET STATISTICS TIME ON
SET STATISTICS IO ON
GO
-- Remove clean buffers & clear plan cache
CHECKPOINT
DBCC DROPCLEANBUFFERS
DBCC FREEPROCCACHE
GO
-- Solution 1
SQL Server parse and compile time:
CPU time = 0 ms, elapsed time = 42 ms.
(4 row(s) affected)
Table 'Worktable'. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'user_visits'. Scan count 1, logical reads 11, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
SQL Server Execution Times:
CPU time = 16 ms, elapsed time = 5 ms.
-- Solution 2
SQL Server parse and compile time:
CPU time = 0 ms, elapsed time = 0 ms.
(4 row(s) affected)
Table 'Worktable'. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'user_visits'. Scan count 1, logical reads 11, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
SQL Server Execution Times:
CPU time = 16 ms, elapsed time = 5 ms.
两种解决方案具有相同的读取次数、工作表等.但是，SUM() 解决方案少了一个运算符.
Both solutions have the same number of reads, work table, etc. However, the SUM() solution has one less operator.
我要给两个回答赞的人+1！！
I am going to give both people who answered a thumbs up +1!!
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