Autofill SQL table field with Datetime value based on input parameter - sql

Question

I have a datetime field in my SQL table. I have created a procedure that takes count as a variable and generates records for the table. If the count is 5 it will generate 5 records.The logic i want is that when i provide 5 as an input parameter the datetime field in the table should be autofilled with values
12/20/2015 9:00
12/20/2015 11:00
12/20/2015 13:00
12/20/2015 15:00
12/20/2015 17:00
So every time a record is inserted into a table,the 2 hours of time should be added.

Answer 1

Recursive CTEs are one way to create records on the fly. The key here is to create an anchor (this is the first SELECT inside the CTE, which is your starting point). And an exit check (which is the WHERE clause).
Read up on MAXRECURSION if you want to create more than 100 records at a time.
Example
DECLARE #RecordsRequired INT = 5;
DECLARE #BaseDateTime SMALLDATETIME = GETDATE();
WITH [Sample] AS
(
/* This CTE uses recursion to create the required number of
* records.
*/
SELECT
1 AS RowNumber,
#BaseDateTime AS [DateTime]
UNION ALL
SELECT
RowNumber + 1 AS RowNumber,
DATEADD(HOUR, 2, [DateTime]) AS [DateTime]
FROM
[Sample]
WHERE
RowNumber < #RecordsRequired
)
SELECT
RowNumber,
[DateTime]
FROM
[Sample]
;
You could also look into WHILE blocks.

Answer 2

Use this code:
------------------ INPUT ------------------------
declare #start_date datetime = '01/01/2000 14:00'
declare #loops int = 5
-------------------------------------------------
declare #i int = 0
while (#i < #loops) begin
select dateadd(hour, #i * 2, #start_date)
set #i = #i + 1
end

Answer 3

Try this without LOOP
Declare #count int = 5,
#incrementer int =2 -- in case if you want to change the incrementer
SELECT Dateadd(hh, num * #incrementer, dates)
FROM (SELECT Cast(CONVERT(VARCHAR(20), Dateadd(dd, 1, Getdate()), 111)
+ ' 9:00 AM' AS DATETIME) AS Dates,
num
FROM (VALUES(0),(1),(2),(3),(4),(5)) TC (num)) A
WHERE num <= #count - 1
SQL FIDDLE DEMO

Answer 4

Please find the sample code below, it contains the logic that you needed. Hope it helps!!
--Create a temp table for sample output
CREATE TABLE #temp
(
CreatedDate datetime
)
--Declaring variables
DECLARE #Count int
DECLARE #TimeCounter int
--intializing values
SET #Count=5
SET #TimeCounter=0
WHILE(#Count>0)
BEGIN
--SELECT getdate()+1
insert into #temp(#temp.CreatedDate) Select DATEADD(hour,#TimeCounter,getdate())
SET #TimeCounter=#TimeCounter+2
SET #Count=#Count-1
END
--Final values
SELECT * FROM #temp tmp
--Dropping table
DROP TABLE #temp

Answer 5

This is one of those problems that's best solved with a numbers table / function. Much less code than recursion or loops, usually faster for anything non-trivial and more reusable too.
The core code you want is
CREATE PROCEDURE usp_PopulateAppointments
(
#StartDateTime datetime2(3),
#Records int,
#Interval int = 120 --Time between appointment slots in minutes. Default to 2h if not manually specified.
)
INSERT INTO Appointments
SELECT
DATEADD(m, #Interval * Number, #StartDateTime)
FROM dbo.udfNumbers(0, #Recs)
I've assumed in this a numbers function that takes #StartAt and #NumberResults. I use one derived from Adam's final code in the comments on http://dataeducation.com/you-require-a-numbers-table/ - in my experience it's faster than a real table, and takes less space too.

Answer 6

Create Table dates
(
datetimefield datetime not null
)
go
Create Procedure FillDateTimeField
#insertxrows int
AS
begin
Declare #LastDateTimeInserted as datetime
set #LastDateTimeInserted = (select isnull(max(datetimefield),getdate()) from Dates)
;WITH norows AS (
SELECT 1 as num, Dateadd(hour,2,#LastDateTimeInserted) as FirstRecord
UNION ALL
SELECT num + 1, dateadd(hour,2,firstrecord) FROM
norows
WHERE num < #insertxrows
)
insert into dates
select firstrecord from norows
end