Incrementing a variable inside a looped INSERT in SQL Server 2012 - sql

Question

How can we be able to include the other column to loop the same as the looped month in this code?
What I'm trying to achieve is the range of $datestart and $dateend should loop the [Data 3] as well.
If [Data 3] is equal to 100, and the range of $datestart and $dateend is 10
Data 3 column should increment from 100,101,102,103,104,105.. and so on up to 110
DECLARE #MYTESTTABLE TABLE
(
[Month] DATE,
[Data 1] INT,
[Data 2] INT,
[Data 3] INT
);
WITH MYLOOP AS
(
SELECT CAST('$datestart' AS DATE) AS [date], '$datavalue' AS [Data 3]
UNION ALL
SELECT DATEADD(MONTH, 1, [date]), [Data 3] = [Data 3] + 1
FROM MYLOOP
WHERE DATEADD(MONTH, 1, [date]) < CAST('$dateend' AS DATE)
)
INSERT INTO #MYTESTTABLE ([Month], [Data 1], [Data 2], [Data 3])
SELECT
LEFT([date], 10) AS [Month], 100 AS [Data 1], 100 AS [Data 2], [Data 3]
FROM
MYLOOP
SELECT *
FROM #MYTESTTABLE
Suppose $datavalue is equal to 100, and it will loop along with the range of the loop from $datestart to $dateend.
Example
The next column (Data 3) should be 100,101,102,103,104,... and so on
How can we achieve this?
I tried doing it like this [Data 3] = [Data 3] + 1 but I get this error:
Types don't match between the anchor and the recursive part in column "Data 3" of recursive query "MYLOOP".

Answer 1

The error message just happens to be the first error that SQL Server picks. There is in fact a great deal wrong with your SQL that SQL Server is not reporting.
Firstly T-SQL uses #variablename to denote variables (not $variablename). Secondly enclosing something in single quotes (') will cause SQL Server to treat it as a literal string. If you enter the following in a Query window:
SELECT CAST('$datestart' as date)
you will get a conversion failed error.
In addition I strongly recommend that you strongly type your variables #datestart and #dateend so that you do not need to use casts.
As an example try the following:
DECLARE #datestart date = '2019-01-01'
DECLARE #dateend date = '2019-11-02'
DECLARE #datavalue int = 100
DECLARE #MYTESTTABLE TABLE ([Month] date, [Data 1] INT, [Data 2] INT, [Data 3] INT);
;WITH MYLOOP AS (
SELECT #datestart AS [date], #datavalue as [Data 3]
UNION ALL
SELECT DATEADD(MONTH, 1, [date]), [Data 3]=[Data 3]+1
FROM MYLOOP
WHERE DATEADD(MONTH, 1, [date]) < #dateend)
INSERT INTO #MYTESTTABLE ([Month], [Data 1], [Data 2], [Data 3])
SELECT [date] AS [Month], 100 AS [Data 1], 100 AS [Data 2], [Data 3]
FROM MYLOOP;
SELECT * FROM #MYTESTTABLE
This will give you data from 2019-01-01 to 2019-11-01. Note I set #dateend as 2019-11-02, because you are using < #dateend. This ensures that you will also get the desired last date. Otherwise you can use <=.