Hey @ah6442,
It seems that n8n is not able to connect to your SQL instance. Can you please check the credentials again and make sure they are correct?
yes i am sure about credentials, its simple
server .\SQLExpress
user id: sa
password: 123
The value for the Server parameter doesn’t look right. You have to pass on a URL. For example, if you’re running it on localhost, you will have to set the value to localhost
sir this is MSSQL not mysql i think localhost will be suitable for mysql not MSSql
Hey @ah6442,
I understand that it is a MSSQL and MySQL, localhost was just an example 
The Server URL you’re passing is not correct. You will have to pass the link of the server where it is hosted. I maybe wrong here, but can you try passing the URL from the address bar of your browser? For example, if the URL in the address bar is https://example.com/abcd, I will pass https://example.com in the Server parameter in n8n.
Let me know if this helps.