Question

我有一个SQL查询，该查询将提取与当前日期（当前设置为今天）匹配的所有数据。

我需要修改它，以便它根据该月的数值拉出一个月内的所有记录。

旧SQL：

WHERE CAST(RecordDate AS DATE) = CAST(GETDATE() AS DATE)

我有一个名为@RecordMonth的入站变量。它是等效于月份的数字（1-12）。我需要提取该数字月份中存在的所有记录。

因此，通过伪编码（带有方括号），查询变为

WHERE CAST(RecordDate AS [MonthPartOfDate]) BETWEEN [FirstDayOf @RecordMonth] AND [LastDayOf @RecordMonth]

有人可以帮忙吗？

Answer 1

一个简单的方法是：

WHERE YEAR(recorddate) = YEAR(GETDATE()) AND
      MONTH(recorddate) = MONTH(GETDATE())

这防止使用索引。要使用索引，我会去：

WHERE recorddate >= DATEFROMPARTS(YEAR(GETDATE()), MONTH(GETDATE()), 1) AND
      recorddate < DATEADD(month, 1, DATEFROMPARTS(YEAR(GETDATE()), MONTH(GETDATE()), 1))

Answer 2

您可以声明两个变量，以便将其视为单独的startdate和enddate：

declare @startdate date = DATEFROMPARTS(YEAR(GETDATE()), MONTH(@RecordMonth), 1)
declare @endddate date = EOMONTH(@startdate)

select . . .
from table t
where (cast(recorddate as date) >= @startdate and 
       cast(recorddate as date) <= @enddate
      );

Answer 3

后期添加但有用。对于许多系统，将日期保存在内存优化表中很有用。可以将其连接到表中以提供简单，可靠的日期查询：

https://www.mssqltips.com/sqlservertip/4054/creating-a-date-dimension-or-calendar-table-in-sql-server/

DECLARE @StartDate DATE = '20000101', @NumberOfYears INT = 30;

-- prevent set or regional settings from interfering with 
-- interpretation of dates / literals

SET DATEFIRST 7;
SET DATEFORMAT mdy;
SET LANGUAGE US_ENGLISH;

DECLARE @CutoffDate DATE = DATEADD(YEAR, @NumberOfYears, @StartDate);

-- this is just a holding table for intermediate calculations:

CREATE TABLE [DateTable]
(
  [date]       DATE PRIMARY KEY, 
  [day]        AS DATEPART(DAY,      [date]),
  [month]      AS DATEPART(MONTH,    [date]),
  FirstOfMonth AS CONVERT(DATE, DATEADD(MONTH, DATEDIFF(MONTH, 0, [date]), 0)),
  [MonthName]  AS DATENAME(MONTH,    [date]),
  [week]       AS DATEPART(WEEK,     [date]),
  [ISOweek]    AS DATEPART(ISO_WEEK, [date]),
  [DayOfWeek]  AS DATEPART(WEEKDAY,  [date]),
  [quarter]    AS DATEPART(QUARTER,  [date]),
  [year]       AS DATEPART(YEAR,     [date]),
  FirstOfYear  AS CONVERT(DATE, DATEADD(YEAR,  DATEDIFF(YEAR,  0, [date]), 0)),
  Style112     AS CONVERT(CHAR(8),   [date], 112),
  Style101     AS CONVERT(CHAR(10),  [date], 101)
);

-- use the catalog views to generate as many rows as we need

INSERT [DateTable]([date]) 
SELECT d
FROM
(
  SELECT d = DATEADD(DAY, rn - 1, @StartDate)
  FROM 
  (
    SELECT TOP (DATEDIFF(DAY, @StartDate, @CutoffDate)) 
      rn = ROW_NUMBER() OVER (ORDER BY s1.[object_id])
    FROM sys.all_objects AS s1
    CROSS JOIN sys.all_objects AS s2
    -- on my system this would support > 5 million days
    ORDER BY s1.[object_id]
  ) AS x
) AS y;

select * from [DateTable]

T-SQL通过入站变量拉入特定月份的数据

3 个答案: