How to select data's from this today,week and month sperately? - sql

Question

I have a problem that is I am unable to resolve as of now.
I need to get the data of
this day, this week and this month
I have a table reminder where I want to select reminders according to
following parameters.
1. Today
2. This Week
3. This Month
The column rdate having the date format in dd-mm-yyyy which is stored as nvarchar
For example
If I execute this weeks query I should get data starting from this week i.e.
If it is Friday I should get data from starting from Sunday to Saturday of that week
How can I get the data as mentioned above. I have searched a lot on internet but I didn't get the solution?
This is the query I have been trying
SELECT
*
FROM
reminder
WHERE
date > DATE_SUB(GETDATE(), INTERVAL 1 DAY)
ORDER BY
rdate DESC;
Where I'm converting nvarchar to date format.

Answer 1

If it's not possible to change the [date] column's data type to DATE, then you will incur a massive performance penalty when trying to filter by date.
Add computed column to table
We can add a computed column that will store the date in the correct format, and then index it for quick searchiing:
ALTER TABLE reminder
ADD Date_Value AS (CONVERT(DATE, '12-05-2016', 105)) PERSISTED;
-- This should yield superior performance
CREATE NONCLUSTERED INDEX IX_Date_Value ON reminder (Date_Value);
Table-valued function to calculate date range
Now, let's create an inline table-valued function to generate the date range for specific period types:
CREATE FUNCTION [dbo].[tvfn_Get_Date_Range](
#Period_Type VARCHAR(100)
)
RETURNS
TABLE
AS RETURN
(
WITH date_range AS(
SELECT CAST(GETDATE() AS DATE) d
-- This line works correctly if your week starts on Sunday
,CAST(DATEADD(WEEK, DATEDIFF(WEEK, '19050101', GETDATE()), '19050101') AS DATE) AS week_start
,CAST(DATEADD(DAY, - DAY(GETDATE()) + 1, GETDATE()) AS DATE) AS month_start
,CAST(DATEADD(MONTH, 1, DATEADD(DAY, - DAY(GETDATE()), GETDATE())) AS DATE) AS month_end
)
SELECT d AS From_Date
,d AS To_Date
FROM date_range
WHERE #Period_Type = 'DAY'
UNION ALL
SELECT week_start
,DATEADD(DAY, 7, week_start)
FROM date_range
WHERE #Period_Type = 'WEEK'
UNION ALL
SELECT month_start
,month_end
FROM date_range
WHERE #Period_Type = 'MONTH'
)
In the above function, week starts on Sunday. If you need this to be configurable, then take a look at the answer to SET DATEFIRST in FUNCTION.
Fast, simple querying now possible
You can now use the two together using a simple query:
SET #Range VARCHAR(100) = 'WEEK'
SELECT *
FROM reminder
CROSS APPLY [dbo].[tvfn_Get_Date_Range](#Range) dr
WHERE Date_Value BETWEEN dr.Date_From AND dr.Date_To

Answer 2

If you can't change the columns data type to Date (or DateTime), you must convert it to date in the query.
Here is one way to get the data for today, this week and this month:
Get records from today:
SELECT *
FROM reminder
WHERE CONVERT(Date, [date], 105) = CAST(GETDATE() as date)
ORDER BY rdate DESC;
Get records from this week:
SELECT *
FROM reminder
WHERE DATEPART(WEEK, CONVERT(Date, [date], 105)) = DATEPART(WEEK, GETDATE())
AND DATEPART(YEAR, CONVERT(Date, [date], 105)) = DATEPART(YEAR, GETDATE())
ORDER BY rdate DESC;
Get records from this Month:
SELECT *
FROM reminder
WHERE DATEPART(MONTH, CONVERT(Date, [date], 105)) = DATEPART(MONTH, GETDATE())
AND DATEPART(YEAR, CONVERT(Date, [date], 105)) = DATEPART(YEAR, GETDATE())
ORDER BY rdate DESC;

Answer 3

To my knowledge, SQL server internally deals with date format as MM/dd/yyyy.
Usually I prefer to save date as string in SQL table since it's easier for inserting and retrieving.
For example, suppose that the column rdate is defined as follows in your table reminder:
[rdate] nvarchar NULL
Then you can customize the select statement for a week as follows:
"Select R.* From reminder R Where CAST(R.rdate as datetime) between
'03/04/2011' AND '03/11/2011'"
And for 10 days as follows:
"Select R.* From reminder R Where CAST(R.rdate as datetime) between
'03/04/2011' AND '03/14/2011'"
And so on. If this is not what you want, please provide more details about your requirements.