T-SQL日期范围在循环中使用动态变量

Question

我有一个包含事务,时间戳和用户的表.

CREATE TABLE [dbo].[Transactions]
(
    [transaction_ts] [datetime] NULL,
    [user_id] [bigint] NULL,
    [transaction_id] [bigint] NULL,
    [item] [varchar](50) NULL
)

对于每一个user_id,我需要选择他们在第一次交易和72小时之后进行的所有交易.

--get first and last timestamps for range
DROP TABLE IF EXISTS #first;

SELECT mt.transaction_ts as first_trans,mt.user_id 
INTO #first
FROM Transactions mt 
INNER JOIN
    (SELECT user_id, MIN(transaction_ts) MinDate
     FROM Transactions
     GROUP BY user_id) t ON mt.user_id = t.user_id AND mt.transaction_ts = t.MinDate;

ALTER TABLE #first
ADD first_trans_plus_72 datetime;

UPDATE #first 
SET first_trans_plus_72 = DATEADD(hour, 72, first_trans)

--loop through user_id and select ranges using variables
DECLARE @Table TABLE (user_id bigint, Id int identity(1,1));

INSERT INTO @Table 
    SELECT DISTINCT user_id 
    FROM #first;

DECLARE @max int;
DECLARE @SQL VARCHAR(MAX);
DECLARE @user_id VARCHAR(max);
DECLARE @first VARCHAR(max);
DECLARE @first_trans_plus_72 VARCHAR(max);
DECLARE @id int = 1;

SELECT @max = MAX(Id) FROM@Table;

WHILE (@id <= @max)
BEGIN
    SELECT @user_id = user_id FROM @Table WHERE Id = @id
    SELECT @first = first_trans FROM #First WHERE user_id = @user_id
    SELECT @first_trans_plus_72 = first_trans_plus_72 FROM #First WHERE user_id = @user_id
    SET @SQL = 'select * from Transactions 
                where transaction_ts between ' + @first + ' and ' + @first_trans_plus_72 + ' 
                and user_id = ' + @user_id + ';'
    PRINT(@SQL)
    EXEC(@SQL)
    SET @id = @id +1
END

这会生成正确的逻辑sql,但datetime变量是字符串,因此查询错误输出.我尝试设置日期时间变量(@first和@first_trans_plus_72作为datetime,但是这导致转换错误.

有更简单的方法吗？

Answer 1

当您可以使用简单查询时,为什么要使用循环？

select t.*
from (select t.*, min(transaction_ts) over (partition by user_id) as min_tts
      from transactions t
     ) t
where t.transaction_ts <= dateadd(hour, 72, min_tts);

通常,最好使用基于集合的操作编写代码.它更简单,表现更好,更好.

您可以将其合并到更新中,但我不认为这是必要的.以上选择交易.您可以用它group by user_id来总结它们 - 比如计算它们或者对值求和.