我有一个包含一组列的表，其中一个是日期列。
我需要计算该列值在同一月份出现的次数。并返回如果一个月，该计数总和超过 3。
例如：
____________________
| DATE | .... |
---------------------
1998-09-02
1998-09-03
1998-10-03
1998-10-04
这必须不返回任何值。因为它没有必要的重复次数。
但这确实：
____________________
| DATE | .... |
---------------------
1998-09-02
1998-09-03
1998-09-12
1998-09-14
1998-10-02
1998-11-21
为 11 月。
适用于 Oracle 数据库。
SELECT
COUNT(date)
, TRUNC(DATE,'MON')
FROM TABLE
GROUP BY TRUNC(DATE,'MON')
HAVING COUNT(DATE) > 3
create table x (date_col date);
insert into x values (date '1998-09-02');
insert into x values (date '1998-09-03');
insert into x values (date '1998-09-12');
insert into x values (date '1998-09-14');
insert into x values (date '1998-10-02');
insert into x values (date '1998-11-21');
SELECT TRUNC(date_col,'MM'), count(*)
FROM x
GROUP BY TRUNC(date_col,'MM')
HAVING count(*) > 3;
这个例子将有所帮助：
create table d1
( event_date date, event_description varchar2(100));
insert into d1 values (sysdate,'Phone Call');
insert into d1 values (sysdate,'Letter');
insert into d1 values (sysdate-50,'Interview');
insert into d1 values (sysdate-50,'Dinner with parents');
insert into d1 values (sysdate-100,'Birthday');
insert into d1 values (sysdate-100,'Holiday');
insert into d1 values (sysdate-100,'Interview');
insert into d1 values (sysdate-100,'Phone Call');
commit;
select * from d1;
EVENT_DATE EVENT_DESCRIPTION
------------------------- -----------------------------------------------
04-MAR-10 14.47.58 Phone Call
04-MAR-10 14.47.58 Letter
13-JAN-10 14.47.58 Interview
13-JAN-10 14.47.58 Dinner with parents
24-NOV-09 14.47.58 Birthday
24-NOV-09 14.47.58 Holiday
24-NOV-09 14.47.58 Interview
24-NOV-09 14.47.58 Phone Call
8 rows selected
您可以看到 Nov-09 是唯一一个超过 3 个事件的月份。
回到您最初的问题，即And return if for 一个月，该计数总和超过 3。以下 SQL 聚合将起作用。
select trunc(event_date,'MONTH'),count('x') from d1
having count('x') > 3 group by trunc(event_date,'MONTH')
或者，使用 to_char 将 Date 类型转换为带有 MON-YYYY 图片的 Char，如下所示：
select to_char(trunc(event_date,'MONTH'),'MON-YYYY') month,
count('x') no_of_occurances from d1 having count('x') > 3 group trunc(event_date,'MONTH')
因此，如果 3 列包含 1999-01-xx 你想要获取它吗？
SELECT YEAR(date), MONTH(date)
FROM table GROUP BY YEAR(date), MONTH(date)
HAVING COUNT(*) > 3
如果您需要包含上部结果的所有行，它应该看起来像这样
SELECT * FROM table
INNER JOIN (
SELECT YEAR(date) as y, MONTH(date) as m
FROM table GROUP BY YEAR(date), MONTH(date)
HAVING COUNT(*) > 3
) as virtualTable
ON virtualTable.y = YEAR(date) AND virtualTable.m = MONTH(date)
理想情况下，您应该创建一个接受您需要的两个条件的存储过程，Month(integer) 和 limit(integer)
在执行以下操作的参数化过程中
SELECT MONTH(Date) AS TheMonth, COUNT(MONTH(Date)) AS TheMonthCount
FROM MyTable
GROUP BY MONTH(Date)
HAVING (COUNT(MONTH(Date)) > @limit) AND (MONTH(Date) = @month)
要同时输出相关月份，您可以使用以下命令
SELECT CAST(YEAR(Date) AS NVARCHAR) + '.' +
CAST(MONTH(Date) AS NVARCHAR) AS 'The ',
MONTH(Date ) AS TheMonth, COUNT(MONTH(Date)) AS TheMonthCount
FROM Audit_Entry
GROUP BY MONTH(Date),
CAST(YEAR(Date) AS NVARCHAR) + '.' +
CAST(MONTH(Date) AS NVARCHAR)
HAVING (COUNT(MONTH(Date)) > @limit) AND (MONTH(Date) = @month)
这应该适用于 mysql 和 mssql：
SELECT MONTH(date), Sum(MONTH(date))
FROM table
GROUP BY date
HAVING Sum(MONTH(date)) > 3
您可以使用 Oracle 的 EXTRACT 方法：
select theMonth, sum(monthCount)
from (
select
extract(MONTH FROM t.theDateColumn) as theMonth,
1 as monthCount
)
group by theMonth
having sum(monthCount) >= 3
目前我手头没有 Oracle 数据库，因此此代码可能无法按原样运行 - 我对此表示歉意。
可能是错的，但猜测：
SELECT SUM(date) FROM table
GROUP BY date where SUM(date) > 3