I am trying to add new item to sharepoint list by using rest api in sql, but I am getting error that I can't deal with. I need to do this this way, because there is need to share information in SP when some information occur in our database. We are using SharePoint 2019 on Premise.

I am getting this error:
{"error":{"code":"-2130575251, Microsoft.SharePoint.SPException","message":{"lang":"en-US","value":"The security validation for this page is invalid and might be corrupted. Please use your web browser's Back button to try your operation again."}}}

From what i read about this error, i should add X-RequestDigest, but after adding code with it, nothing changed and I still get this error.
This is code I am testing:

DECLARE @URL NVARCHAR(MAX) = 'http://<server>/<site>/_api/contextinfo';  
DECLARE @HeaderValue NVARCHAR(MAX) = 'application/json; odata=verbose';  
Declare @Object as Int;  
Declare @ResponseText as Varchar(8000);  
DECLARE @RequestDigest NVARCHAR(MAX);  
DECLARE @ret INT;  
EXEC @ret = sp_OACreate 'MSXML2.XMLHTTP', @Object OUT;  
IF @ret <> 0 RAISERROR('Unable to open HTTP connection.', 10, 1);  
Exec sp_OAMethod @Object, 'open', NULL, 'post', @URL, 'False';  
Exec sp_OAMethod @Object, 'setRequestHeader', NULL, 'Accept', @HeaderValue;  
Exec sp_OAMethod @Object, 'send';  
Exec sp_OAMethod @Object, 'responseText', @ResponseText OUTPUT;  
IF((Select @ResponseText) <> '')  
BEGIN  
     DECLARE @json NVARCHAR(MAX) = (Select @ResponseText)  
     SELECT @RequestDigest = req  
     FROM OPENJSON(@json)  
          WITH (  
                 req NVARCHAR(30) '$.d.GetContextWebInformation.FormDigestValue'  
BEGIN  
     DECLARE @ErroMsg NVARCHAR(30) = 'No data found.';  
     Print @ErroMsg;  
Exec sp_OADestroy @Object  
print @RequestDigest;  
set @URL = '<server>/<site>/_api/lists/getbytitle(''test'')/items';  
DECLARE @Body AS VARCHAR(8000) =  
  "__metadata": {  
    "type": "SP.Data.TestListItem"  
  "Title": "Test"  
DECLARE @len int  
SET @len = len(@body)  
EXEC @ret = sp_OACreate 'MSXML2.XMLHTTP', @Object OUT;  
IF @ret <> 0 RAISERROR('Unable to open HTTP connection.', 10, 1);  
Exec sp_OAMethod @Object, 'Open', null, 'Post', @URL, 'False';  
Exec sp_OAMethod @Object, 'setRequestHeader', null, 'Accept', @HeaderValue;  
EXEC sp_OAMethod @Object, 'setRequestHeader', null, 'Content-Type', @HeaderValue;  
EXEC sp_OAMethod @Object, 'SETRequestHeader', null, 'Content-Length', @len;  
EXEC sp_OAMethod @Object, 'SETRequestHeader', null, 'X-RequestDigest', @RequestDigest;  
--EXEC sp_OAMethod @Object, 'SETRequestBody', null, 'Body', @body;  
Exec sp_OAMethod @Object, 'send', null, @Body;  
Exec sp_OAMethod @Object, 'responseText', @ResponseText OUTPUT;  
IF CHARINDEX('false',(SELECT @ResponseText)) > 0  
BEGIN  
 SELECT @ResponseText As 'Message'  
BEGIN  
 SELECT @ResponseText As 'Details'  
EXEC sp_OADestroy @Object  
The security validation for this page is invalid    
You are using the very old MSXML2.XMLHTTP, which doesn't support any security feature, no https, no encrytion and so on; I don't think you get that working.    

And SQL Server is not the right place for such operations.    

Better use other tools like PowerShell:  SharePoint PowerShell cmdlet    
						
Agree with OlafHelper's suggestion.
In summary, SQL Query isn't the right way to call SharePoint Rest API.
You can use the PowerShell below to call SharePoint 2013 On-Premise Rest API for adding item:
$url="http://server/sites/SiteName/_api/lists/GetByTitle('YourListTitle')/items"
#the url to get request digest
$url1="http://server/sites/SiteName/_api/contextinfo"                    
$url2="http://server/sites/SiteName/_api/lists/GetByTitle('YourListTitle')"
$credentials=Get-Credential
#getting request digest
$RequestDigest=Invoke-RestMethod -Uri $url1 -Method POST -Credential $credentials
$RequestDigest=$RequestDigest.GetContextWebInformation.FormDigestValue
#getting ListItemEntityTypeFullName
$List = Invoke-RestMethod -uri $url2 -Credential $credentials
$ListItemEntityTypeFullName = $list.entry.content.properties.ListItemEntityTypeFullName
$ListItemEntityTypeFullName
$body = "{ '__metadata': { 'type': '$ListItemEntityTypeFullName' }, 'Title': 'Hello'}"
$header = @{
"accept" = "application/json;odata=verbose"
"X-RequestDigest" = $RequestDigest
Invoke-RestMethod -Method Post -Uri $url -Body $body -ContentType "application/json;odata=verbose" -Headers $header -Credential $credentials
						
@Riwut Libinuko      

As I said in first post, we need this functionality to be restarting daily, automatically and also be connected to SQL to retrieve information when to create new element in list. I know how to do this side functionality in SQL, so it was my first pick.     

I suppose that powershell scripts can also be initiated in this way and can connect to sql server. If I am not wrong?    

But also we are using SQL Server Agent and Jobs daily. I wanted to be consistent in it, because I am afraid if I will be putting some scripts here and there, on this or that server, in time, it can be forgotten and after a while we wouldn't know why something could not work properly. Of course if there is no other way I will stick with this.